BiglooA ``practical Scheme compiler''User manual for version 3.1aMay 2008

5. Bigloo A ``practical Scheme compiler'' User manual for version 3.1a May 2008 -- Standard Library

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top: | Bigloo A ``practical Scheme compiler'' User manual for version 3.1a May 2008

Standard Library

Chapters

This chapter presents the Bigloo standard library. Bigloo is mostly R5RS compliant but it proposes many extensions to this standard. In a first section (Scheme Library) the Bigloo R5RS support is presented. This section also contains various function that are not standard (for instance, various functions used to manage a file system). Then, in the following sections (Serialization, Bit Manipulation, and System Programming Bigloo specific extensions are presented. Bigloo input and output facilities constitue a large superset of the standard Scheme definition. For this reason they are presented in a separate section (Input and Output).

### 5.1 Scheme Library

When the definition of a procedure or a special form is the same in Bigloo and Scheme, we just mention its name; otherwise, we explain it and qualify it as a ``bigloo procedure''.

### 5.1.1 Booleans

The standard boolean objects are `#t` and `#f`. Note: the empty list is true.

not obj | library procedure

`not` returns `#t` if `obj` is false, and returns `#f` otherwise.

    (not #t)                               => #f
    (not 3)                                => #f
    (not (list 3))                         => #f
    (not #f)                               => #t
    (not '())                              => #f
    (not (list))                           => #f
    (not 'nil)                             => #f

boolean? obj | library procedure

`Boolean?` returns `#t` if `obj` is either `#t` or `#f` and returns `#f` otherwise.

    (boolean? #f)                          => #t
    (boolean? 0)                           => #f
    (boolean? '())                         => #f

### 5.1.2 Equivalence predicates

eqv? obj1 obj2 | procedure

eq? obj1 obj2 | procedure

`eqv?` and `eq?` are equivalent in Bigloo.

    (eq? 'a 'a)                            =>  #t
    (eq? '(a) '(a))                        =>  unspecified
    (eq? (list 'a) (list 'a))              =>  #f
    (eq? "a" "a")                          =>  unspecified
    (eq? "" "")                            =>  unspecified
    (eq? '() '())                          =>  #t
    (eq? 2 2)                              =>  unspecified
    (eq? #\A #\A)                          =>  unspecified
    (eq? car car)                          =>  #t
    (let ((n (+ 2 3)))
      (eq? n n))                           =>  unspecified
    (let ((x '(a)))
      (eq? x x))                           =>  #t
    (let ((x '#()))
      (eq? x x))                           =>  #t
    (let ((p (lambda (x) x)))
      (eq? p p))                           =>  #t

Since Bigloo implements `eqv?` as `eq?`, the behavior is not always conforming to R5RS.

    (eqv? 'a 'a)                           =>  #t
    (eqv? 'a 'b)                           =>  #f
    (eqv? 2 2)                             =>  #t
    (eqv? '() '())                         =>  #t
    (eqv? 100000000 100000000)             =>  #t
    (eqv? (cons 1 2) (cons 1 2))           =>  #f
    (eqv? (lambda () 1)
          (lambda () 2))                   =>  #f
    (eqv? #f 'nil)                         =>  #f
    (let ((p (lambda (x) x)))
      (eqv? p p))                          =>  unspecified

The following examples illustrate cases in which the above rules do not fully specify the behavior of `eqv?`. All that can be said about such cases is that the value returned by `eqv?` must be a boolean.

    (eqv? "" "")                           =>  unspecified
    (eqv? '#() '#())                       =>  unspecified
    (eqv? (lambda (x) x)
          (lambda (x) x))                  =>  unspecified
    (eqv? (lambda (x) x)
          (lambda (y) y))                  =>  unspecified

    (define gen-counter
      (lambda ()
        (let ((n 0))
          (lambda () (set! n (+ n 1)) n))))
    (let ((g (gen-counter)))
      (eqv? g g))                          =>  #t
    (eqv? (gen-counter) (gen-counter))
                                           =>  #f
    (define gen-loser
      (lambda ()
        (let ((n 0))
          (lambda () (set! n (+ n 1)) 27))))
    (let ((g (gen-loser)))
      (eqv? g g))                          =>  #t
    (eqv? (gen-loser) (gen-loser))
                                           =>  unspecified

    (letrec ((f (lambda () (if (eqv? f g) 'both 'f)))
             (g (lambda () (if (eqv? f g) 'both 'g))))
      (eqv? f g))
                                           =>  unspecified

    (letrec ((f (lambda () (if (eqv? f g) 'f 'both)))
             (g (lambda () (if (eqv? f g) 'g 'both))))
      (eqv? f g))
                                           =>  #f
    (eqv? '(a) '(a))                       =>  unspecified
    (eqv? "a" "a")                         =>  unspecified
    (eqv? '(b) (cdr '(a b)))               =>  unspecified
    (let ((x '(a)))
      (eqv? x x))                          =>  #t

equal? obj1 obj2 | library procedure

    (equal? 'a 'a)                         =>  #t
    (equal? '(a) '(a))                     =>  #t
    (equal? '(a (b) c)
            '(a (b) c))                    =>  #t
    (equal? "abc" "abc")                   =>  #t
    (equal? 2 2)                           =>  #t
    (equal? (make-vector 5 'a)
            (make-vector 5 'a))            =>  #t
    (equal? (lambda (x) x)
            (lambda (y) y))                =>  unspecified

See r5rs, Equivalence predicates, for more details.

### 5.1.3 Pairs and lists

The form `()` is illegal.

pair? obj | procedure

cons a d | procedure

pair-or-null? obj | bigloo procedure

Returns `#t` if `obj` is either a pair or the empty list. Otherwise it returns `#f`.

car pair | procedure

cdr pair | procedure

set-car! pair obj | procedure

set-cdr! pair obj | procedure

caar pair | library procedure

cadr pair | library procedure

...

cdddar pair | library procedure

cddddr pair | library procedure

null? obj | library procedure

list? obj | library procedure

list obj ... | library procedure

length list | library procedure

append list ... | library procedure

append! list ... | bigloo procedure

A destructive append.

reverse list | library procedure

reverse! list | bigloo procedure

A destructive reverse.

list-ref list k | library procedure

take list k | library procedure

drop list k | library procedure

list-tail list k | library procedure

`list-ref` returns the `k` element of the list.
`take` returns a new list made of the first `k` element of the list.
`Drop` and `list-tail` returns the sublist of `list` obtained by omitting the first `k` elements.

last-pair list | bigloo procedure

Returns the last pair in the nonempty, possibly improper, `list`.

memq obj list | library procedure

memv obj list | library procedure

member obj list | library procedure

assq obj alist | library procedure

assv obj alist | library procedure

assoc obj alist | library procedure

remq obj list | bigloo procedure

Returns a new list which is a copy of `list` with all items `eq?` to `obj` removed from it.

remq! obj list | bigloo procedure

Same as `remq` but in a destructive way.

delete obj list [eq equal?] | bigloo procedure

Returns a new list which is a copy of `list` with all items `equal?` to `obj` deleted from it.

delete! obj list [eq equal?] | bigloo procedure

Same as `delete` but in a destructive way.

cons* obj ... | bigloo procedure

Returns an object formed by consing all arguments together from right to left. If only one `obj` is supplied, that `obj` is returned.

every? fun clist1 clist2 ... | bigloo procedure

Applies the predicate across the lists, returning true if the predicate returns non-false on every application.

    (every < '(1 2 3) '(2 3 4))            => #t
    (every < '(1 2 3) '(2 3 0))            => #f

any? fun clist1 clist2 ... | bigloo procedure

Applies the predicate across the lists, returning true if the predicate returns non-false for at least one application.

    (any < '(1 2 3) '(2 3 4))            => #t
    (any < '(1 2 3) '(2 3 0))            => #t

every fun clist1 clist2 ... | bigloo procedure

Applies the function `fun` across the lists, returning the last non-false if the function returns non-false on every application. If non-false, the result of `every` is the last value returned by the last application of `fun`.

    (every < '(1 2 3) '(2 3 4))            => #t
    (every < '(1 2 3) '(2 3 0))            => #f

any fun clist1 clist2 ... | bigloo procedure

Applies the function `fun` across the lists, returning non-false if the function returns non-false for at least one application. If non-false, the result of `any` is the first non-false value returned by `fun`.

    (any < '(1 2 3) '(2 3 4))            => #t
    (any < '(1 2 3) '(2 3 0))            => #t

find pred clist | bigloo procedure

Return the first element of `clist` that satisfies predicate `pred`; false if no element does.

    (find even? '(3 1 4 1 5 9))          => 4

Note that `find` has an ambiguity in its lookup semantics -- if find returns `#f`, you cannot tell (in general) if it found a `#f` element that satisfied `pred`, or if it did not find any element at all. In many situations, this ambiguity cannot arise -- either the list being searched is known not to contain any `#f` elements, or the list is guaranteed to have an element satisfying pred. However, in cases where this ambiguity can arise, you should use find-tail instead of find -- find-tail has no such ambiguity:

        (cond ((find-tail pred lis) => (lambda (pair) ...)) ; Handle (CAR PAIR)
              (else ...)) ; Search failed.

find-tail pred clist | bigloo procedure

Return the first pair of `clist` whose car satisfies `pred`. If no pair does, return false.
`find-tail` can be viewed as a general-predicate variant of the member function.
Examples:

        (find-tail even? '(3 1 37 -8 -5 0 0)) => (-8 -5 0 0)
        (find-tail even? '(3 1 37 -5)) => #f

        ;; MEMBER X LIS:
        (find-tail (lambda (elt) (equal? x elt)) lis)

        In the circular-list case, this procedure "rotates" the list.

make-list n [fill] | bigloo procedure

Returns an `n`-element list, whose elements are all the value `fill`. If the `fill` argument is not given, the elements of the list may be arbitrary values.

    (make-list 4 'c)                     => (c c c c)

list-tabulate n init-proc | bigloo procedure

Returns an `n`-element list. Element i of the list, where 0 <= i < `n`, is produced by `(init-proc i)`. No guarantee is made about the dynamic order in which `init-proc` is applied to these indices.

    (list-tabulate 4 values)             => (0 1 2 3)

list-split list n [filler] | bigloo procedure

list-split list n [filler] | bigloo procedure

Split a `list` into a list of lists of length `n`. Last smaller list is filled with `filler`.

    (list-split '(1 2 3 4 5 6 7 8) 3 0) => ((1 2 3) (4 5 6) (7 8 0))
    (list-split (iota 10) 3)            => ((0 1 2) (3 4 5) (6 7 8) (9))
    (list-split (iota 10 3) '-1)      => ((0 1 2) (3 4 5) (6 7 8) (9 -1 -1))

iota count [start step] | bigloo procedure

Returns a list containing the elements

    (start start+step ... start+(count-1)*step)

The `start` and `step` parameters default to `0` and `1`, respectively. This procedure takes its name from the APL primitive.

    (iota 5) => (0 1 2 3 4)
    (iota 5 0 -0.1) => (0 -0.1 -0.2 -0.3 -0.4)

list-copy l | bigloo procedure

tree-copy l | bigloo procedure

The function `list-copy` copies the spine of the of the list. The function `tree-copy` recursively copies its arguments, descending only into the list cells.

delete-duplicates list [eq equal?] | bigloo procedure

delete-duplicates! list [eq equal?] | bigloo procedure

`delete-duplicates` removes duplicate elements from the `list` argument. If there are multiple equal elements in the argument list, the result list only contains the first or leftmost of these elements in the result. The order of these surviving elements is the same as in the original list -- `delete-duplicates` does not disorder the list (hence it is useful for "cleaning up" association lists).
The `equal` parameter is used to compare the elements of the list; it defaults to `equal?`. If x comes before y in list, then the comparison is performed (= x y). The comparison procedure will be used to compare each pair of elements in list no more than once; the order in which it is applied to the various pairs is not specified.
`delete-duplicates` is allowed to share common tails between argument and result lists -- for example, if the list argument contains only unique elements, it may simply return exactly this list.

See r5rs, Pairs and lists, for more details.

### 5.1.4 Symbols

Symbols are case sensitive and the reader is case sensitive too. So:

    (eq? 'foo 'FOO) => #f
    (eq? (string->symbol "foo") (string->symbol "FOO")) => #f

Symbols may contain special characters (such as #\Newline or #\Space). Such symbols that have to be read must be written: `|[^]+|`. The function `write` uses that notation when it encounters symbols containing special characters.

    (write 'foo) => foo
    (write 'Foo) =>Foo
    (write '|foo bar|) => |foo bar|

symbol? obj | procedure

symbol->string symbol | procedure

Returns the name of the symbol as a string. Modifying the string result of `symbol->string` could yield incoherent programs. It is better to copy the string before any physical update. For instance, don't write:

    (string-downcase! (symbol->string 'foo))

See r5rs, Symbols, for more details.
but prefer:

    (string-downcase (symbol->string 'foo))

string->symbol string | procedure

string->symbol-ci string | bigloo procedure

symbol-append symbol ... | bigloo procedure

`String->symbol` returns a symbol whose name is `string`. `String->symbol` respects the case of `string`. `String->symbol-ci` returns a symbol whose name is `(string-upcase `string`)`. `Symbol-append` returns a symbol whose name is the concatenation of all the `symbol`'s names.

gensym [obj] | bigloo procedure

Returns a new fresh symbol. If `obj` is provided and is a string or a symbol, it is used as prefix for the new symbol.

symbol-plist symbol-or-keyword | bigloo procedure

Returns the property-list associated with `symbol-or-keyword`.

getprop symbol-or-keyword key | bigloo procedure

Returns the value that has the key `eq?` to `key` from the `symbol-or-keyword`'s property list. If there is no value associated with `key` then `#f` is returned.

putprop! symbol-or-keyword key val | bigloo procedure

Stores `val` using `key` on `symbol-or-keyword`'s property list.

remprop! symbol-or-keyword key | bigloo procedure

Removes the value associated with `key` in the `symbol-or-keyword`'s property list. The result is unspecified.

Here is an example of properties handling:

    (getprop 'a-sym 'a-key)       => #f
    (putprop! 'a-sym 'a-key 24)
    (getprop 'a-sym 'a-key)       => 24
    (putprop! 'a-sym 'a-key2 25)
    (getprop 'a-sym 'a-key)       => 24
    (getprop 'a-sym 'a-key2)      => 25
    (symbol-plist 'a-sym)         => (a-key2 25 a-key 24)
    (remprop! 'a-sym 'a-key)
    (symbol-plist 'a-sym)         => (a-key2 25)
    (putprop! 'a-sym 'a-key2 16)
    (symbol-plist 'a-sym)         => (a-key2 16)

### 5.1.5 Keywords

Keywords constitute an extension to Scheme required by Dsssl [Dsssl96]. Keywords syntax is either `<ident>:` or `:<ident>`.
Keywords are autoquote and case sensitive. So

    (eq? toto: TOTO:) => #f

The colon character (`:`) does not belong to they keyword. Hence

    (eq? toto: :toto) => #t

keyword? obj | bigloo procedure

keyword->string keyword | bigloo procedure

string->keyword string | bigloo procedure

keyword->symbol keyword | bigloo procedure

symbol->keyword symbol | bigloo procedure

### 5.1.6 Numbers

Bigloo has only three kinds of numbers: fixnum, long fixnum and flonum. Operations on complexes and rationals are not implemented but for compatibility purposes, the functions `complex?` and `rational?` exist. (In fact, `complex?` is the same as `number?` and `rational?` is the same as `real?` in Bigloo.) The accepted prefixes are `#b`, `#o`, `#d`, `#x`, `#e`, `#ex`, `#l`, `#lx`, and `#z`. For each generic arithmetic procedure, Bigloo provides two specialized procedures, one for fixnums and one for flonums. The names of these two specialized procedures is the name of the original one suffixed by `fx` (fixnum), `fl` (flonum), `elong` (exact C long), `llong` (exact C long long), and `bx` (big integer). A fixnum has the size of a C `long` minus 2 bits. A flonum has the size of a C `double`. An elong has the size of a C long. An llong has the size of a C long long. A big integer has an unbounded size.

number? obj | procedure

real? obj | procedure

integer? obj | procedure

complex? x | bigloo procedure

rational? x | bigloo procedure

fixnum? obj | bigloo procedure

flonum? obj | bigloo procedure

These two procedures are type checkers on types `integer` and `real`.

elong? obj | bigloo procedure

llong? obj | bigloo procedure

The `elong?` procedures is a type checker for "hardware" integers, that is integers that have the very same size has the host platform permits (e.g., 32 bits or 64 bits integers). The `llong?` procedure is a type checker for "hardware" long long integers. Exact integers literal are introduced with the special `#e` and `#ex` prefixes. Exact long integers literal are introduced with the special `#l` and `#lx` prefixes.

bignum? obj | bigloo procedure

This type checker tests if its argument is a big integer.

make-elong int | bigloo procedure

make-llong int | bigloo procedure

Create an exact fixnum integer from the fixnum value `int`.

minvalfx | bigloo procedure

maxvalfx | bigloo procedure

minvalelong | bigloo procedure

maxvalelong | bigloo procedure

minvalllong | bigloo procedure

maxvalllong | bigloo procedure

Returns the minimal value (respectively the maximal value) for fix integers.

exact? z | procedure

inexact? z | procedure

zero? z | library procedure

positive? z | library procedure

negative? z | library procedure

odd? n | library procedure

even? n | library procedure

zerofx? z | library procedure

positivefx? z | library procedure

negativefx? z | library procedure

oddfx? n | library procedure

evenfx? n | library procedure

zerofl? z | library procedure

positivefl? z | library procedure

negativefl? z | library procedure

oddfl? n | library procedure

evenfl? n | library procedure

zeroelong? z | library procedure

positiveelong? z | library procedure

negativeelong? z | library procedure

oddelong? n | library procedure

evenelong? n | library procedure

zerollong? z | library procedure

positivellong? z | library procedure

negativellong? z | library procedure

oddllong? n | library procedure

evenllong? n | library procedure

zerobx? z | library procedure

positivebx? z | library procedure

negativebx? z | library procedure

oddbx? n | library procedure

evenbx? n | library procedure

min x1 x2 ... | library procedure

max x1 x2 ... | library procedure

minfx x1 x2 ... | bigloo procedure

maxfx x1 x2 ... | bigloo procedure

minfl x1 x2 ... | bigloo procedure

maxfl x1 x2 ... | bigloo procedure

minbx x1 x2 ... | bigloo procedure

maxbx x1 x2 ... | bigloo procedure

= z1 z2 z3 ... | procedure

=fx i1 i2 | bigloo procedure

=fl r1 r2 | bigloo procedure

=elong r1 r2 | bigloo procedure

=llong r1 r2 | bigloo procedure

=bx r1 r2 | bigloo procedure

< z1 z2 z3 ... | procedure

<fx i1 i2 | bigloo procedure

<fl r1 r2 | bigloo procedure

<elong r1 r2 | bigloo procedure

<lllong r1 r2 | bigloo procedure

<bx r1 r2 | bigloo procedure

> z1 z2 z3 ... | procedure

>fx i1 i2 | bigloo procedure

>fl r1 r2 | bigloo procedure

>elong r1 r2 | bigloo procedure

>lllong r1 r2 | bigloo procedure

>bx r1 r2 | bigloo procedure

<= z1 z2 z3 ... | procedure

<=fx i1 i2 | bigloo procedure

<=fl r1 r2 | bigloo procedure

<=elong r1 r2 | bigloo procedure

<=llong r1 r2 | bigloo procedure

<=bx r1 r2 | bigloo procedure

>= z1 z2 z3 ... | procedure

>=fx i1 i2 | bigloo procedure

>=fl r1 r2 | bigloo procedure

>=elong r1 r2 | bigloo procedure

>=llong r1 r2 | bigloo procedure

>=bx r1 r2 | bigloo procedure

+ z ... | procedure

+fx i1 i2 | bigloo procedure

+fl r1 r2 | bigloo procedure

+elong r1 r2 | bigloo procedure

+llong r1 r2 | bigloo procedure

+bx r1 r2 | bigloo procedure

* z ... | procedure

*fx i1 i2 | bigloo procedure

*fl r1 r2 | bigloo procedure

*elong r1 r2 | bigloo procedure

*llong r1 r2 | bigloo procedure

*bx r1 r2 | bigloo procedure

- z | procedure

- z1 z2 ... | procedure

-fx i1 i2 | bigloo procedure

-fl r1 r2 | bigloo procedure

-elong r1 r2 | bigloo procedure

-llong r1 r2 | bigloo procedure

-bx r1 r2 | bigloo procedure

negfx i | bigloo procedure

negfl r | bigloo procedure

negelong r | bigloo procedure

negllong r | bigloo procedure

negbx r | bigloo procedure

These two functions implement the unary function `-`.

/ z1 z2 | procedure

/ z1 z2 ... | procedure

/fx i1 i2 | bigloo procedure

/fl r1 r2 | bigloo procedure

/elong r1 r2 | bigloo procedure

/llong r1 r2 | bigloo procedure

/bx r1 r2 | bigloo procedure

abs z | library procedure

absfl z | bigloo procedure

quotient z1 z2 | procedure

quotientelong z1 z2 | procedure

quotientllong z1 z2 | procedure

remainder z1 z2 | procedure

remainderelong z1 z2 | procedure

remainderllong z1 z2 | procedure

remainderfl z1 z2 | procedure

modulo z1 z2 | procedure

gcd z ... | procedure

lcm z ... | procedure

floor z | procedure

floorfl z | procedure

ceiling z | procedure

ceilingfl z | procedure

truncate z | procedure

truncatefl z | procedure

round z | procedure

roundfl z | procedure

random z | bigloo procedure

seed-random! z | bigloo procedure

the `random` function returns a pseudo-random integer between 0 and `z`.
If no seed value is provided, the `random` function is automatically seeded with a value of 1.

exp z | procedure

expfl z | procedure

log z | procedure

logfl z | procedure

sin z | procedure

sinfl z | procedure

cos z | procedure

cosfl z | procedure

tan z | procedure

tanfl z | procedure

asin z | procedure

asinfl z | procedure

acos z | procedure

acosfl z | procedure

atan z1 z2 | procedure

atanfl z1 z2 | procedure

sqrt z | procedure

sqrtfl z | procedure

expt z1 x2 | procedure

exptfl z1 x2 | procedure

exact->inexact z | procedure

inexact->exact z | procedure

number->string z | procedure

integer->string i [radix 10] | bigloo procedure

integer->string/padding i padding [radix 10] | bigloo procedure

elong->string i [radix 10] | bigloo procedure

llong->string i [radix 10] | bigloo procedure

real->string z | bigloo procedure

unsigned->string i [radix 16] | bigloo procedure

The function `integer->string/padding` converts its arguments into a string with a left padding filled of characters `0`.

    (integer->string/padding 3 5)       => "00003"

The function `unsigned->string` only accepts the following radixes: `2`, `8`, and `16`. It converts its argument into an unsigned representation.

    (unsigned->string 123 16)           => "7b"
    (unsigned->string -123 16)          => "ffffff85"

string->number string [radix 10] | procedure

string->real string | bigloo procedure

string->elong string radix | bigloo procedure

string->llong string radix | bigloo procedure

string->bignum string radix | bigloo procedure

Bigloo implements a restricted version of `string->number`. If `string` denotes a floating point number then, the only radix `10` may be send to `string->number`. That is:

    (string->number "1243" 16)          => 4675
    (string->number "1243.0" 16)        -|
    # *** ERROR:bigloo:string->number
    # Only radix `10' is legal for floating point number -- 16
    (string->elong "234456353")         => #e234456353

In addition, `string->number` does not support radix encoded inside `string`. That is:

    (string->number "#x1243")          => #f

fixnum->flonum i | bigloo procedure

flonum->fixnum r | bigloo procedure

elong->fixnum i | bigloo procedure

fixnum->elong r | bigloo procedure

llong->fixnum i | bigloo procedure

fixnum->llong r | bigloo procedure

elong->flonum i | bigloo procedure

flonum->elong r | bigloo procedure

llong->flonum i | bigloo procedure

flonum->llong r | bigloo procedure

For efficiency, `string->real` and `string->integer` do not test whether the string can be read as a number. Therefore the result might be wrong if the string cannot be read as a number.
These last procedures implement the natural translation from and to fixnum, flonum, elong, and llong.

See r5rs, Numerical operations, for more details.

### 5.1.7 Characters

Bigloo knows one more named characters `#\tab`, `#\return`, and `#\null` in addition to the `#\space` and `#\newline` of R5RS.
A new alternate syntax exists for characters: `#a<ascii-code>` where `<ascii-code>` is the three digit decimal ascii number of the character to be read. Thus, for instance, the character `#\space` can be written `#a032`.

char? obj | procedure

char=? char1 char2 | procedure

char<? char1 char2 | procedure

char>? char1 char2 | procedure

char<=? char1 char2 | procedure

char>=? char1 char2 | procedure

char-ci=? char1 char2 | library procedure

char-ci<? char1 char2 | library procedure

char-ci>? char1 char2 | library procedure

char-ci<=? char1 char2 | library procedure

char-ci>=? char1 char2 | library procedure

char-alphabetic? char | library procedure

char-numeric? char | library procedure

char-whitespace? char | library procedure

char-upper-case? char | library procedure

char-lower-case? char | library procedure

char->integer char | procedure

integer->char i | procedure

char-upcase char | library procedure

char-downcase char | library procedure

### 5.1.8 UCS-2 Characters

UCS-2 Characters are two byte encoded characters. They can be read with the syntax: `#u<unicode>` where `<unicode>` is the four digit hexadecimal unicode value of the character to be read. Thus, for instance, the character `#\space` can be written `#u0020`.

ucs2? obj | bigloo procedure

ucs2=? ucs2a ucs2b | bigloo procedure

ucs2<? ucs2a ucs2b | bigloo procedure

ucs2>? ucs2a ucs2b | bigloo procedure

ucs2<=? ucs2a ucs2b | bigloo procedure

ucs2>=? ucs2a ucs2b | bigloo procedure

ucs2-ci=? ucs2a ucs2b | bigloo procedure

ucs2-ci<? ucs2a ucs2b | bigloo procedure

ucs2-ci>? ucs2a ucs2b | bigloo procedure

ucs2-ci<=? ucs2a ucs2b | bigloo procedure

ucs2-ci>=? ucs2a ucs2b | bigloo procedure

ucs2-alphabetic? ucs2 | bigloo procedure

ucs2-numeric? ucs2 | bigloo procedure

ucs2-whitespace? ucs2 | bigloo procedure

ucs2-upper-case? ucs2 | bigloo procedure

ucs2-lower-case? ucs2 | bigloo procedure

ucs2->integer ucs2 | bigloo procedure

integer->ucs2 i | bigloo procedure

ucs2->char ucs2 | bigloo procedure

char->ucs2 char | bigloo procedure

ucs2-upcase ucs2 | bigloo procedure

ucs2-downcase ucs2 | bigloo procedure

### 5.1.9 Strings

There are three different syntaxes for strings in Bigloo: traditional, foreign or Unicode. The traditional syntax for strings may conform to the Revised Report, see r5rs, Lexical structure. With the foreign syntax, C escape sequences are interpreted as specified by ISO-C. In addition, Bigloo's reader evaluate `\x??` sequence as an hexadecimal escape character. For Unicode syntax, see Unicode (UCS-2) Strings. Only the reader distinguishes between these three appearances of strings; i.e., there is only one type of string at evaluation-time. The regular expression describing the syntax for foreign string is: `#"([^"]|\")*"`. Escape characters are controlled by the parameter `bigloo-strict-r5rs-strings` (see Parameters).
The library functions for string processing are:

string? obj | procedure

string-null? s | SRFI-13 procedure

Is `s` an empty string?

make-string k | procedure

make-string k char | procedure

string char ... | library procedure

string-length string | procedure

string-ref string k | procedure

string-set! string k char | procedure

string=? string1 string2 | library procedure

This function returns `#t` if the `string1` and `string2` are made of the same characters. It returns `#f` otherwise.

substring=? string1 string2 len | bigloo procedure

This function returns `#t` if `string1` and `string2` have a common prefix of size `len`.

    (substring=? "abcdef" "ab9989898" 2)
       => #t
    (substring=? "abcdef" "ab9989898" 3)
       => #f

substring-at? string1 string2 offset [len] | bigloo procedure

substring-ci-at? string1 string2 offset [len] | bigloo procedure

This function returns `#t` if `string2` is at position `offset` in the string `string1`. It returns `#f` otherwise.

    (substring-at? "abcdefghij" "def" 3)
       => #t
    (substring-at? "abcdefghij" "def" 2)
       => #f
    (substring-at? "abcdefghij" "defz" 3)
       => #f
    (substring-at? "abcdefghij" "defz" 3 3)
       => #t

string-ci=? string1 string2 | library procedure

substring-ci=? string1 string2 len | bigloo procedure

substring-ci-at? string1 string2 pos | bigloo procedure

string<? string1 string2 | library procedure

string>? string1 string2 | library procedure

string<=? string1 string2 | library procedure

string>=? string1 string2 | library procedure

string-ci<? string1 string2 | library procedure

string-ci>? string1 string2 | library procedure

string-ci<=? string1 string2 | library procedure

string-ci>=? string1 string2 | library procedure

string-index string charset [start 0] | bigloo procedure

string-index-right string charset [start len-1] | bigloo procedure

Returns the first occurrence of a character of `char-or-set` in `string`. The argument `charset` is either a character or a string. If no character is found, `string-index` returns `#f`.

string-contains string1 string2 [start 0] | bigloo procedure

string-contains-ci string1 string2 [start 0] | bigloo procedure

Does string s1 contain string s2?
Return the index in `string1` where `string2` occurs first as a substring, or false.
`string-contains-ci` is the case-insensitive variant. Case-insensitive comparison is done by case-folding characters with the operation:

    (char-downcase (char-upcase c))

string-compare3 string1 string2 | bigloo procedure

string-compare3-ci string1 string2 | bigloo procedure

This function compares `string1` and `string2`. It returns a negative integer if `string1` < `string2`. It returns zero if the `string1` equal `string2`. It returns a positive integer if `string1` > `string2`.

string-natural-compare3 string1 string2 | bigloo procedure

string-natural-compare3-ci string1 string2 | bigloo procedure

This function compares `string1` and `string2` according to a natural string order. It returns a negative integer if `string1` < `string2`. It returns zero if the `string1` equal `string2`. It returns a positive integer if `string1` > `string2`.

    (string-natural-compare "foo" "foo")
       => 0
    (string-natural-compare "foo0" "foo1")
       => -1
    (string-natural-compare "foo1" "foo0")
       => 1
    (string-natural-compare "rfc822.txt" "rfc1.txt")
       => -1
    (string-natural-compare "rfc1.txt" "rfc2086.txt")
       => -1
    (string-natural-compare "rfc2086.txt" "rfc1.txt")
       => 1
    (string-natural-compare "rfc822.txt" "rfc2086.txt")
       => -1
    (string-natural-compare "a0" "a1")
       => -1
    (string-natural-compare "a1" "a1a")
       => -1
    (string-natural-compare "a1a" "a1b")
       => -1
    (string-natural-compare "a1b" "a2")
       => -1
    (string-natural-compare "a2" "a10")
       => -1
    (string-natural-compare "a10" "a20")
       => -1
    (string-natural-compare "a2" "a20")
       => -1
    (string-natural-compare "x2-g8" "x2-y7")
       => -1
    (string-natural-compare "1.001" "1.002")
       => -1
    (string-natural-compare "1.002" "1.010")
       => -1
    (string-natural-compare "1.010"  "1.02")
       => 1
    (string-natural-compare "1.02" "1.1")
       => -1
    (string-natural-compare "1.1" "1.02")
       => 1
    (string-natural-compare "1.02" "1.3")
       => -1

substring string start end | library procedure

`string` must be a string, and `start` and `end` must be exact integers satisfying:

      0 <= START <= END <= (string-length STRING)

`substring` returns a newly allocated string formed from the characters of `STRING` beginning with index `START` (inclusive) and ending with index `END` (exclusive).

    (substring "abcdef" 0 5)
       => "abcde"
    (substring "abcdef" 1 5)
       => "bcde"

string-shrink! string end | library procedure

`string` must be a string, and `end` must be an exact integers satisfying:

      0 <= END <= (string-length STRING)

`string-shrink!` returns a newly allocated string formed from the characters of `STRING` beginning with index 0 (inclusive) and ending with index `END` (exclusive). As much as possible `string-shrink!` changes the argument `string`. That is, as much as possible, and for the back-ends that enable it, `string-shrink!` operate a side effect on its argument.

    (let ((s (string #\a #\b #\c #\d #\e)))
       (set! s (string-shrink! s 3))
       s)
       => "abc"

string-append string ... | library procedure

string->list string | library procedure

list->string list | library procedure

string-copy string | library procedure

string-fill! string char | bigloo procedure

Stores `char` in every element of the given `string` and returns an unspecified value.

string-downcase string | bigloo procedure

Returns a newly allocated version of string where each upper case letter is replaced by its lower case equivalent.

string-upcase string | bigloo procedure

Returns a newly allocated version of string where each lower case letter is replaced by its upper case equivalent.

string-capitalize string | bigloo procedure

Builds a newly allocated capitalized string.

string-downcase! string | bigloo procedure

Physically downcases the `string` argument.

string-upcase! string | bigloo procedure

Physically upcases the `string` argument.

string-capitalize! string | bigloo procedure

Physically capitalized the `string` argument.

string-for-read string | bigloo procedure

Returns a copy of `string` with each special character replaced by an escape sequence.

blit-string! string1 o1 string2 o2 len | bigloo procedure

Fill string `s2` starting at position `o2` with `len` characters taken out of string `s1` from position `o1`.

    (let ((s (make-string 20 #\-)))
    	(blit-string! "toto" 0 s 16 4)
    	s)
       => "----------------toto"

string-replace string char1 char2 | bigloo procedure

string-replace! string char1 char2 | bigloo procedure

Replace all the occurrence of `char1` by `char2` in `string`. The function `string-replace` returns a newly allocated string. The function `string-replace!` modifies its first argument.

string-split string | bigloo procedure

string-split string delimiters | bigloo procedure

Parses `string` and returns a list of tokens ended by a character of the `delimiters` string. If `delimiters` is omitted, it defaults to a string containing a space, a tabulation and a newline characters.

    (string-split "/usr/local/bin" "/") => ("usr" "local" "bin")
    (string-split "once   upon a time") => ("once" "upon" "a" "time")

string-prefix-length s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-suffix-length s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-prefix-length-ci s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-suffix-length-ci s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

Return the length of the longest common prefix/suffix of the two strings. For prefixes, this is equivalent to the "mismatch index" for the strings (modulo the starti index offsets).
The optional start/end indices restrict the comparison to the indicated substrings of s1 and s2.

string-prefix? s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-suffix? s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-prefix-ci? s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

string-suffix-ci? s1 s2 [start1 end1 start2 end2] | SRFI-13 procedure

Is s1 a prefix/suffix of s2?
The optional start/end indices restrict the comparison to the indicated substrings of s1 and s2.

string-hex-intern string | bigloo procedure

string-hex-intern! string | bigloo procedure

Converts an hexadecimal `string` of `n` characters into an actual string of `n/2` characters.

    (string-hex-intern "4a4b4c") => "JKL"

string-hex-extern string | bigloo procedure

Converts a `string` into a hexadecimal representation.

    (string-hex-extern "JKL") => "4a4b4c"

### 5.1.10 Unicode (UCS-2) Strings

UCS-2 strings cannot be read by the standard reader but UTF-8 strings can. The special syntax for UTF-8 is described by the regular expression: `#u"([^]|\")*"`.
The library functions for Unicode string processing are:

ucs2-string? obj | bigloo procedure

make-ucs2-string k | bigloo procedure

make-ucs2-string k char | bigloo procedure

ucs2-string k ... | bigloo procedure

ucs2-string-length s-ucs2 | bigloo procedure

ucs2-string-ref s-ucs2 k | bigloo procedure

ucs2-string-set! s-ucs2 k char | bigloo procedure

ucs2-string=? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string-ci=? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string<? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string>? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string<=? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string>=? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string-ci<? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string-ci>? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string-ci<=? s-ucs2a s-ucs2b | bigloo procedure

ucs2-string-ci>=? s-ucs2a s-ucs2b | bigloo procedure

subucs2-string s-ucs2 start end | bigloo procedure

ucs2-string-append s-ucs2 ... | bigloo procedure

ucs2-string->list s-ucs2 | bigloo procedure

list->ucs2-string chars | bigloo procedure

ucs2-string-copy s-ucs2 | bigloo procedure

ucs2-string-fill! s-ucs2 char | bigloo procedure

Stores `char` in every element of the given s-ucs2 and returns an unspecified value.

ucs2-string-downcase s-ucs2 | bigloo procedure

Builds a newly allocated ucs2-string with lower case letters.

ucs2-string-upcase s-ucs2 | bigloo procedure

Builds a new allocated ucs2-string with upper case letters.

ucs2-string-downcase! s-ucs2 | bigloo procedure

Physically downcases the `s-ucs2` argument.

ucs2-string-upcase! s-ucs2 | bigloo procedure

Physically upcases the `s-ucs2` argument.

ucs2-string->utf8-string s-ucs2 | bigloo procedure

utf8-string->ucs2-string `string` | bigloo procedure

Convert UCS-2 strings to (or from) UTF-8 encoded ascii strings.

iso-latin->utf8 string | bigloo procedure

iso-latin->utf8! string | bigloo procedure

utf8->iso-latin `string` | bigloo procedure

utf8->iso-latin! `string` | bigloo procedure

Encode and decode iso-latin strings into utf8. The functions `iso-latin->utf8-string!` and `utf8->iso-latin!` may return, as result, the string they receive as argument.

### 5.1.11 Vectors

Vectors are not autoquoted objects.

vector? obj | procedure

make-vector k | procedure

make-vector k obj | procedure

vector obj ... | library procedure

vector-length vector | procedure

vector-ref vector k | procedure

vector-set! vector k obj | procedure

vector->list vector | library procedure

list->vector list | library procedure

vector-fill! vector obj | library procedure

Stores `obj` in every element of `vector`. For instance:

    (let ((v (make-vector 5 #f)))
       (vector-fill! v #t)
       v)

copy-vector vector len | bigloo procedure

Allocate a new vector of size `len` and fills it with the first `len` element of `vector`. The new length `len` may be bigger than the old vector length.

vector-copy vector start end | bigloo procedure

`vector` must be a vector, and `start` and `end` must be exact integers satisfying:

      0 <= START <= END <= (vector-length VECTOR)

`vector-copy` returns a newly allocated vector formed from the elements of `VECTOR` beginning with index `START` (inclusive) and ending with index `END` (exclusive).

    (vector-copy '#(1 2 3 4) 0 4)
       => '#(1 2 3 4)
    (vector-copy '#(1 2 3 4) 1 3)
       => '#(2 3)

vector-copy! target tstart source [sstart [send]] | bigloo procedure

Copies a block of elements from `source` to `target`, both of which must be vectors, starting in target at `tstart` and starting in source at `sstart`, ending when `send - sstart` elements have been copied. It is an error for `target` to have a length less than `tstart + (send - sstart)`. `Sstart` defaults to `0` and `send` defaults to the length of `source`.

See r5rs, Vectors, for more details.

### 5.1.12 Homogeneous Vectors (SRFI-4)

Bigloo fully supports SRFI-4 specification of homogeneous vectors (see http://srfi.schemers.org/srfi-4/srfi-4.html).
Each homogeneous vector is represented by a Bigloo type. That is:

- `::s8vector` signed exact integer in the range -(2^7) to (2^7)-1
- `::u8vector` unsigned exact integer in the range 0 to (2^8)-1
- `::s16vector` signed exact integer in the range -(2^15) to (2^15)-1
- `::u16vector` unsigned exact integer in the range 0 to (2^16)-1
- `::s32vector` signed exact integer in the range -(2^31) to (2^31)-1
- `::u32vector` unsigned exact integer in the range 0 to (2^32)-1
- `::s64vector` signed exact integer in the range -(2^63) to (2^63)-1
- `::u64vector` unsigned exact integer in the range 0 to (2^64)-1
- `f32vector` inexact small real
- `f64vector` inexact largest real

Each homogeneous vector datatype has an external representation which is supported by the read and write procedures and by the program parser. Each datatype also has a set of associated predefined procedures analogous to those available for Scheme's heterogeneous vectors.
As noted by Marc Feeley's specification, for each value of TAG in { s8, u8, s16, u16, s32, u32, s64, u64, f32,f64 }, if the datatype TAGvector is supported, then

- the external representation of instances of the datatype TAGvector is #TAG( ...elements... ).
  For example, `#u8(0 #e1e2 #xff)` is an u8vector of length 3 containing 0, 100 and 255; `#f64(-1.5)` is an f64vector of length 1 containing -1.5.
  Note that the syntax for float vectors conflicts with Standard Scheme which parses `#f32()` as 3 objects: `#f`, `32` and `()`. For this reason, conformance to this SRFI implies this minor nonconformance to Standard Scheme.
  This external representation is also available in program source code. For example, `(set! x '#u8(1 2 3))` will set x to the object `#u8(1 2 3)`. Literal homogeneous vectors must be quoted just like heterogeneous vectors must be. Homogeneous vectors can appear in quasiquotations but must not contain unquote or unquote-splicing forms (i.e. ``(,x #u8(1 2))` is legal but ``#u8(1 ,x 2)` is not). This restriction is to accomodate the many Scheme systems that use the read procedure to parse programs.
- the following predefined procedures are available:

  TAGvector? obj | SRFI-4 procedure

  make-TAGvector n [ TAGvalue ] | SRFI-4 procedure

  TAGvector TAGvalue ... | SRFI-4 procedure

  TAGvector-length TAGvect | SRFI-4 procedure

  TAGvector-ref TAGvect i | SRFI-4 procedure

  TAGvector-set! TAGvect i TAGvalue | SRFI-4 procedure

  TAGvector->list TAGvect | SRFI-4 procedure

  list->TAGvector TAGlist | SRFI-4 procedure

  where obj is any Scheme object, n is a nonnegative exact integer, i is a nonnegative exact integer less than the length of the vector, TAGvect is an instance of the TAGvector datatype, TAGvalue is a number of the type acceptable for elements of the TAGvector datatype, and TAGlist is a proper list of numbers of the type acceptable for elements of the TAGvector datatype.
  It is an error if TAGvalue is not the same type as the elements of the TAGvector datatype (for example if an exact integer is passed to f64vector). If the fill value is not specified, the content of the vector is unspecified but individual elements of the vector are guaranteed to be in the range of values permitted for that type of vector.

### 5.1.13 Control features

procedure? obj | procedure

apply proc arg1 ... args | procedure

map proc list1 list2 ... | library procedure

map! proc list1 list2 ... | bigloo procedure

for-each proc list1 list2 ... | library procedure

filter pred list ... | library procedure

filter! pred list ... | library procedure

Strip out all elements of `list` for which the predicate `pred` is not true. The second version `filter!` is destructive:

    (filter number? '(1 2 #\a "foo" foo 3)) => (1 2 3)
    (let ((l (list 1 2 #\a "foo" 'foo 3)))
       (set! l (filter! number? l))
       l)                                   => (1 2 3)

append-map proc list1 list2 ... | library procedure

append-map! proc list1 list2 ... | library procedure

The expression

      (append-map f clist1 clist2 ...)

is equivalent to:

      (apply append (map f clist1 clist2 ...))

The expression

      (append-map! f clist1 clist2 ...)

is equivalent to:

      (apply append! (map f clist1 clist2 ...))

filter-map pred list ... | bigloo procedure

As `map` but only none `#f` values are accumulated in the resulting list. The Bigloo implementation complies with the SRFI-1 description.

    (filter-map (lambda (x) (if (number? x) '- #f)) '(1 2 #\a "foo" foo 3)) => (- - -)

sort proc obj | bigloo procedure

sort obj proc | bigloo procedure

Sorts `obj` according to `proc` test. The argument `obj` can either be a vector or a list. In either case, a copy of the argument is returned. For instance:

    (let ((l '(("foo" 5) ("bar" 6) ("hux" 1) ("gee" 4))))
       (sort (lambda (x y) (string<? (car x) (car y))) l))
       => ((bar 6) (foo 5) (gee 4) (hux 1))

The second form (which uses `obj` before `proc` ensures backward compatibility with old Lisp systems, and older Bigloo versions. It is deprecated.

force promise | library procedure

call/cc proc | bigloo procedure

This function is the same as the `call-with-current-continuation` function of the R5RS, see r5rs, call-with-current-continuation, but it is necessary to compile the module with the `-call/cc` option to use it, see Section See The Bigloo command line.
Note: Since `call/cc` is difficult to compile efficiently, one might consider using `bind-exit` instead. For this reason, we decided to enable `call/cc` only with a compiler option.

bind-exit escape body | bigloo syntax

This form provides an escape operator facility. `bind-exit` evaluates the `body`, which may refer to the variable `escape` which will denote an ``escape function'' of one argument: when called, this escape function will return from the `bind-exit` form with the given argument as the value of the `bind-exit` form. The `escape` can only be used while in the dynamic extent of the form. Bindings introduced by `bind-exit` are immutable.

    (bind-exit (exit)
     (for-each (lambda (x)
                 (if (negative? x)
                     (exit x)))
               '(54 0 37 -3 245 19))
     #t)                                  => -3

    (define list-length
      (lambda (obj)
        (bind-exit (return)
         (letrec ((r (lambda (obj)
                        (cond ((null? obj) 0)
                              ((pair? obj)
                               (+ (r (cdr obj)) 1))
                              (else (return #f))))))
              (r obj)))))

    (list-length '(1 2 3 4))               => 4
    (list-length '(a b . c))               => #f

unwind-protect expr protect | bigloo syntax

This form provides protections. Expression `expr` is evaluated. If this evaluation requires the invocation of an escape procedure (a procedure bounded by the `bind-exit` special form), `protect` is evaluated before the control jump to the exit procedure. If `expr` does not raise any exit procedure, `unwind-protect` has the same behaviour as the `begin` special form except that the value of the form is always the value of `expr`.

    (define (my-open f)
       (if (file-exists? f)
           (let ((port (open-input-file f)))
              (if (input-port? port)
                  (unwind-protect
                     (bar port)
                     (close-input-port port))))))

dynamic-wind before thunk after | procedure

Calls `thunk` without arguments, returning the result(s) of this call. `Before` and `after` are called, also without arguments, as required by the following rules (note that in the absence of calls to continuations captured using `call/cc` the three arguments are called once each, in order). `Before` is called whenever execution enters the dynamic extent of the call to `thunk` and `after` is called whenever it exits that dynamic extent. The dynamic extent of a procedure call is the period between when the call is initiated and when it returns. In Scheme, because of `call/cc`, the dynamic extent of a call may not be a single, connected time period. It is defined as follows:

- The dynamic extent is entered when execution of the body of the called procedure begins.
- The dynamic extent is also entered when execution is not within the dynamic extent and a continuation is invoked that was captured (using `call/cc`) during the dynamic extent.
- It is exited when the called procedure returns.
- It is also exited when execution is within the dynamic extent and a continuation is invoked that was captured while not within the dynamic extent.

If a second call to `dynamic-wind` occurs within the dynamic extent of the call to `thunk` and then a continuation is invoked in such a way that the `after`s from these two invocations of `dynamic-wind` are both to be called, then the `after` associated with the second (inner) call to `dynamic-wind` is called first.
If a second call to `dynamic-wind` occurs within the dynamic extent of the call to `thunk` and then a continuation is invoked in such a way that the `before`s from these two invocations of `dynamic-wind` are both to be called, then the `before` associated with the first (outer) call to `dynamic-wind` is called first.
If invoking a continuation requires calling the `before` from one call to `dynamic-wind` and the `after` from another, then the `after` is called first.
The effect of using a captured continuation to enter or exit the dynamic extent of a call to `before` or `after` is undefined.

    (let ((path '())
          (c #f))
      (let ((add (lambda (s)
                   (set! path (cons s path)))))
        (dynamic-wind
          (lambda () (add 'connect))
          (lambda ()
            (add (call/cc
                   (lambda (c0)
                     (set! c c0)
                     'talk1))))
          (lambda () (add 'disconnect)))
        (if (< (length path) 4)
            (c 'talk2)
            (reverse path))))

       => (connect talk1 disconnect connect talk2 disconnect)

unspecified | bigloo procedure

Returns the unspecified (noted as `#unspecified`) object with no specific property.

try exp handler | bigloo syntax

This form is documented in Section Errors and Assertions.

values obj ... | procedure

Delivers all of its arguments to its continuation. Except for continuations created by the `call-with-values` procedure, all continuations take exactly one value. `Values` might be defined as follows:

    (define (values . things)
      (call/cc
        (lambda (cont) (apply cont things))))

call-with-values producer consumer | procedure

Calls its `producer` argument with no values and a continuation that, when passed some values, calls the `consumer` procedure with those values as arguments. The continuation for the call to `consumer` is the continuation of the call to `call-with-values`.

    (call-with-values (lambda () (values 4 5))
                      (lambda (a b) b))
        => 5
    (call-with-values * -)
        => -1

multiple-value-bind (var ...) producer exp ... | bigloo syntax

receive (var ...) producer exp ... | bigloo syntax

Evaluates `exp` ... in a environment where `var` ... are bound from the evaluation of `producer`. The result of `producer` must be a call to `values` where the number of argument is the number of bound variables.

    (define (bar a)
       (values (modulo a 5) (quotient a 5)))

    (define (foo a)
       (multiple-value-bind (x y)
          (bar a)
          (print x " " y)))

    (foo 354)
       -| 4 70

### 5.2 Input and output

This section describes Scheme operation for reading and writing data. The section Files describes functions for handling files.

### 5.2.1 Library functions

call-with-input-file string proc | library procedure

call-with-output-file string proc | library procedure

These two procedures call `proc` with one argument, a port obtained by opening `string`. See r5rs, Ports, for more details.

    (call-with-input-file "/etc/passwd"
       (lambda (port)
          (let loop ((line (read-line port)))
             (if (not (eof-object? line))
                 (begin
                    (print line)
                    (loop (read-line port)))))))

input-port? obj | procedure

input-string-port? obj | procedure

output-port? obj | procedure

output-string-port? obj | procedure

port? obj | procedure

input-port-name obj | bigloo procedure

output-port-name obj | bigloo procedure

Returns the file name for which `obj` has been opened.

input-port-timeout-set! port time | bigloo (>=2.8b) procedure

output-port-timeout-set! port time | bigloo (>=2.8b) procedure

These two functions limit the time an read or write operation may last. If the `time` limit (expressed in microseconds) exceeded, an exception of time `&io-timeout-error` is raised.

output-port-close-hook port | bigloo procedure

output-port-close-hook-set! port proc | bigloo procedure

Returns (resp. sets) the close hook of the output `port`. The close hook is a procedure of one argument, the closed port. The hook is invoked after the `port` is closed.

input-port-close-hook port | bigloo procedure

input-port-close-hook-set! port proc | bigloo procedure

Returns (resp. sets) the close hook of the input `port`. The close hook is a procedure of one argument, the closed port.
Example:

    (let ((p (open-input-string "/etc/passwd")))
      (input-port-close-hook-set! p (lambda () (display 'done)))
      ...
      (close-input-port p))

input-port-reopen! obj | bigloo procedure

Re-open the input port `obj`. That is, re-start reading from the first character of the input port.

current-input-port | procedure

current-output-port | procedure

current-error-port | bigloo procedure

with-input-from-file string thunk | optional procedure

with-input-from-string string thunk | optional procedure

with-input-from-procedure procedure thunk | optional procedure

with-output-to-file string thunk | optional procedure

with-error-to-file string thunk | bigloo procedure

with-output-to-string thunk | bigloo procedure

with-output-to-procedure procedure thunk | bigloo procedure

with-error-to-string thunk | bigloo procedure

with-error-to-procedure procedure thunk | bigloo procedure

A port is opened from file `string`. This port is made the current input port (resp. the current output port or the current error port) and `thunk` is called. See r5rs, Ports, for more details.

    (with-input-from-file "/etc/passwd"
       (lambda ()
          (let loop ((line (read-line (current-input-port))))
             (if (not (eof-object? line))
                 (begin
                    (print line)
                    (loop (read-line (current-input-port))))))))

with-input-from-port port thunk | bigloo procedure

with-output-to-port port thunk | bigloo procedure

with-error-to-port port thunk | bigloo procedure

`with-input-from-port`, `with-output-to-port` and `with-error-to-port` all suppose `port` to be a legal port. They call `thunk` making `port` the current input (resp. output or error) port. None of these functions close `port` on the continuation of `thunk`.

    (with-output-to-port (current-error-port)
       (lambda () (display "hello")))

open-input-file file-name | procedure

If `file-name` is a regular file name, `open-input-file` behaves as the function defined in the Scheme report. If `file-name` starts with special prefixes it behaves differently. Here are the recognized prefixes:

- `|` (a string made of the characters `#\|` and `#\space`) Instead of opening a regular file, Bigloo opens an input pipe. The same syntax is used for output file.

      (define pin (open-input-file "| cat /etc/passwd"))
      (define pout (open-output-file "| wc -l"))

      (display (read pin) pout)
      (close-input-port pin)
      (newline pout)
      (close-output-port pout)

- `pipe:` Same as `|` .
- `file:` Opens a regular file.
- `gzip:` Opens a port on a gzipped filed. This is equivalent to `open-input-gzip-file`. Example:

      (with-input-from-file "gzip:bigloo.tar.gz"
         (lambda ()
            (send-chars (current-input-port) (current-output-port))))

- `string:` Opens a port on a string. This is equivalent to `open-input-string`. Example:

      (with-input-from-file "string:foo bar Gee"
         (lambda ()
            (print (read))
            (print (read))
            (print (read))))
         -| foo
         -| bar
         -| Gee

- `http:server/path` Opens an http connection on `server` and open an input file on file `path`.
- `http:server:port-number/path` Opens an http connection on `server`, on port number `port` and open an input file on file `path`.
- `ftp:server/path` Opens an http connection on `server` and open an input file on file `path`.
- `ressource:` Opens a JVM ressource file. Opening a `ressource:` file in non JVM backend always return `#f`. On the JVM backend it returns a input port if the ressource exists. Otherwise, it returns `#f`.

open-input-gzip-file file-name | bigloo procedure

open-input-gzip-port input-port | bigloo procedure

Open respectively a gzipped file for input and a port on a gzipped stream. Note that closing a gzip port opened from a port `pi` does not close the `pi` port.

    (let ((p (open-input-gzip-file "bigloo.tar.gz")))
       (unwind-protect
          (read-line p1)
          (close-input-port p)))

    (let* ((p1 (open-input-file "bigloo.tar.gz"))
           (p2 (open-input-gzip-port p1)))
       (unwind-protect
          (read-line p2)
          (close-input-port p2)
          (close-input-port p1)))

open-input-string string [start 0] | bigloo procedure

Returns an `input-port` able to deliver characters from `string`.

open-input-c-string string | bigloo procedure

Returns an `input-port` able to deliver characters from C `string`. The buffer used by the input port is the exact same string as the argument. That is, no buffer is allocated.

open-input-procedure procedure | bigloo procedure

Returns an `input-port` able to deliver characters from `procedure`. Each time a character has to be read, the `procedure` is called. This procedure may returns a string of characters, or the boolean `#f`. This last value stands for the end of file.
Example:

    (let ((p (open-input-procedure (let ((s #t))
    				  (lambda ()
    				     (if s
    					 (begin
                                                (set! s #f)
                                                "foobar")
    					 s))))))
       (read))

open-output-file file-name | procedure

The same syntax as `open-input-file` for file names applies here. When a file name starts with `|` , Bigloo opens an output pipe instead of a regular file.

append-output-file file-name | bigloo procedure

If `file-name` exists, this function returns an `output-port` on it, without removing it. New output will be appended to `file-name`. If `file-name` does not exist, it is created.

open-output-string | bigloo procedure

This function returns an output string port. This object has almost the same purpose as `output-port`. It can be used with all the printer functions which accept `output-port`. An output on a output string port memorizes all the characters written. An invocation of `flush-output-port` or `close-output-port` on an output string port returns a new string which contains all the characters accumulated in the port.

get-output-string output-port | bigloo procedure

Given an output port created by `open-output-string`, returns a string consisting of the characters that have been output to the port so far.

open-output-procedure proc [flush] | bigloo procedure

This function returns an output procedure port. This object has almost the same purpose as `output-port`. It can be used with all the printer functions which accept `output-port`. An output on a output procedure port invokes the `proc` procedure each time it is used for writing. That is, `proc` is invoked with a string denoting the displayed characters. When the function `flush-output-port` is called on such a port, the function optional `flush` procedure is invoked.

close-input-port input-port | procedure

close-output-port output-port | procedure

According to R5RS, the value returned is unspecified. However, if output-port was created using `open-output-string`, the value returned is the string consisting of all characters sent to the port.

input-port-name input-port | bigloo procedure

Returns the name of the file used to open the `input-port`.

input-port-position port | bigloo procedure

output-port-position port | bigloo procedure

Returns the current position (a character number), in the `port`.

set-input-port-position! port pos | bigloo procedure

set-output-port-position! port pos | bigloo procedure

These functions set the file position indicator for `port`. The new position, measured in bytes, is specified by `pos`. It is an error to seek a port that cannot be changed (for instance, a string or a console port). The result of these functions is unspecified. An error is raised if the position cannot be changed.

input-port-reopen! input-port | bigloo procedure

This function re-opens the input `input-port`. That is, it reset the position in the `input-port` to the first character.

read [input-port] | procedure

read/case case [input-port] | bigloo procedure

read-case-sensitive [input-port] | bigloo procedure

read-case-insensitive [input-port] | bigloo procedure

Read a lisp expression. The case sensitivity of `read` is unspecified. If have to to enforce a special behavior regarding the case, use `read/case`, `read-case-sensitive` or `read-case-insensitive`. Let us consider the following source code: The value of the `read/case`'s `case` argument may either be `upcase`, `downcase` or `sensitive`. Using any other value is an error.

    (define (main argv)
       (let loop ((exp (read-case-sensitive)))
          (if (not (eof-object? exp))
              (begin
                 (display "exp: ")
                 (write exp)
                 (display " [")
                 (display exp)
                 (display "]")
                 (print " eq?: " (eq? exp 'FOO) " " (eq? exp 'foo))
                 (loop (read-case-sensitive))))))

Thus:

    > a.out
    foo
      -| exp: foo [foo] eq?: #f #t
    FOO
      -| exp: FOO [FOO] eq?: #t #f

read/rp grammar port | bigloo procedure

read/lalrp lalrg rg port [emptyp] | bigloo procedure

These functions are fully explained in Regular Parsing, and Lalr Parsing.

read-char [port] | procedure

read-byte [port] | procedure

peek-char [port] | procedure

peek-byte [port] | procedure

eof-object? obj | procedure

char-ready? [port] | procedure

As specified in the R5Rs, r5rs, Ports, `char-ready?` returns `#t` if a character is ready on the input `port` and returns `#f` otherwise. If `char-ready` returns `#t` then the next `read-char` operation on the given `port` is guaranteed not to hang. If the `port` is at end of file then `char-ready?` returns `#t`. `Port` may be omitted, in which case it defaults to the value returned by `current-input-port`.
When using `char-ready?` consider the latency that may exists before characters are available. For instance, executing the following source code:

    (let* ((proc (run-process "/bin/ls" "-l" "/bin" output: pipe:))
           (port (process-output-port proc)))
       (let loop ((line (read-line port)))
          (print "char ready " (char-ready? port))
          (if (eof-object? line)
              (close-input-port port)
              (begin
                 (print line)
                 (loop (read-line port))))))

Produces outputs such as:

    char ready #f
    total 7168
    char ready #f
    -rwxr-xr-x    1 root     root         2896 Sep  6  2001 arch
    char ready #f
    -rwxr-xr-x    1 root     root        66428 Aug 25  2001 ash
    char ready #t
    ...

For a discussion of Bigloo processes, see Process.
Note: Thanks to Todd Dukes for the example and the suggestion of including it this documentation.

read-line [input-port] | bigloo procedure

Reads characters from `input-port` until a `#\Newline`, a `#\Return` or an `end of file` condition is encountered. `read-line` returns a newly allocated string composed of the characters read.

read-lines [input-port] | bigloo procedure

Accumulates all the line of an `input-port` into a list.

read-of-strings [input-port] | bigloo procedure

Reads a sequence of non-space characters on `input-port`, makes a string of them and returns the string.

read-string [input-port] | bigloo procedure

Reads all the characters of `input-port` into a string.

read-chars size [input-port] | bigloo procedure

read-chars! buf size [input-port] | bigloo procedure

The function `read-chars` returns a newly allocated strings made of `size` characters read from `input-port` (or from `(current-input-port)` if `input-port` is not provided). If less than `size` characters are available on the input port, the returned string is smaller than `size`. Its size is the number of available characters.
The function `read-char!` fills the buffer `buf` with at most `size` characters.

port->string-list input-port | bigloo procedure

Returns a list of strings composed of the elements of `input-port`.

port->list input-port reader | bigloo procedure

port->sexp-list input-port | bigloo procedure

`Port->list` applies reader to port repeatedly until it returns EOF, then returns a list of results. `Port->list-sexp` is equivalent to `(port->list read port)`.

send-chars input-port output-port [len] [offset] | bigloo procedure

Transfer the characters from `input-port` to `output-port`. This procedure is sometimes mapped to a system call (such as `sendfile` under Linux) and might thus be more efficient than copying the ports by hand. The optional argument `offset` specifies an offset from which characters of `input-port` are sent. The function `send-chars` returns the number of characters sent.

read-fill-string! s o len [input-port] | bigloo procedure

Fills the string `s` starting at offset `o` with at most `len` characters read from the input port `input-port` (or from `(current-input-port)` if `input-port` is not provided). This function returns the number of fill characters (which may be smaller than `len` if less characters are available).
Example:

    (let ((s (make-string 10 #\-)))
       (with-input-from-string "abcdefghijlkmnops"
          (lambda ()
             (read-fill-string! s 3 5)
             s)))
       => ---abcde--

write obj [output-port] | library procedure

display obj [output-port] | library procedure

print obj ... | bigloo procedure

This procedure allows several objects to be displayed. When all these objects have been printed, `print` adds a newline.

display* obj ... | bigloo procedure

This function is similar to `print` but does not add a newline.

fprint output-port obj ... | bigloo procedure

This function is the same as `print` except that a port is provided.

write-char char [output-port] | procedure

write-byte byte [output-port] | procedure

These procedures write a char (respec. a byte, i.e., in integer in the range 0..255) to the `output-port`.

newline [output-port] | procedure

flush-output-port output-port | bigloo procedure

This procedure flushes the output port `output-port`.

format format-string [objs] | bigloo procedure

Note: Many thanks to Scott G. Miller who is the author of SRFI-28. Most of the documentation of this function is copied from the SRFI documentation.
Accepts a message template (a Scheme String), and processes it, replacing any escape sequences in order with one or more characters, the characters themselves dependent on the semantics of the escape sequence encountered.
An escape sequence is a two character sequence in the string where the first character is a tilde `~`. Each escape code's meaning is as follows:

- `~a` The corresponding value is inserted into the string as if printed with display.
- `~s` The corresponding value is inserted into the string as if printed with write.
- `~%` A newline is inserted.
- `~~` A tilde `~` is inserted.

`~a` and `~s`, when encountered, require a corresponding Scheme value to be present after the format string. The values provided as operands are used by the escape sequences in order. It is an error if fewer values are provided than escape sequences that require them.
`~%` and `~~` require no corresponding value.

    (format "Hello, ~a" "World!")
       -| Hello, World!
    (format "Error, list is too short: ~s~%" '(one "two" 3))
       -| Error, list is too short: (one "two" 3)

printf format-string [objs] | bigloo procedure

fprintf port format-string [objs] | bigloo procedure

Formats `objs` to the current output port or to the specified `port`.

pp obj [output-port] | bigloo procedure

Pretty print `obj` on `output-port`.

*pp-case* | bigloo variable

Sets the variable to `respect`, `lower` or `upper` to change the case for pretty-printing.

*pp-width* | bigloo variable

The width of the pretty-print.

write-circle obj [output-port] | bigloo procedure

Display recursive object `obj` on `output-port`. Each component of the object is displayed using the `write` library function.

display-circle obj [output-port] | bigloo procedure

Display recursive object `obj` on `output-port`. Each component of the object is displayed using the `display` library function.
For instance:

    (define l (list 1 2 3))
    (set-car! (cdr l) l)
    (set-car! (cddr l) l)
    (display-circle l)  -| #0=(1 #0# #0#)

display-string string output-port | bigloo procedure

display-substring string start end output-port | bigloo procedure

`String` must be a string, and `start` and `end` must be exact integers satisfying `0 <= start <= end <= (string-length string)`.
`Display-substring` displays a string formed from the characters of string beginning with index `start` (inclusive) and ending with index `end` (exclusive).

password [prompt] | bigloo procedure

Reads a password from the current input port. The reading stops when the user hits the ,(code "Enter") key.

### 5.2.2 mmap

The `mmap` function asks to map a file into memory. This memory area can be randomly accessed as a string. In general using `mmap` improves performance in comparison with equivalent code using regular ports.

mmap? obj | bigloo procedure

Returns `#t` if and only if `obj` has been produced by `open-mmap`. Otherwise, it returns `#f`.

open-mmap path [mode] | bigloo procedure

Maps a file `path` into memory. The optional argument `mode` specifies how the file is open. The argument can be:

- `read: #t` The memory can be read
- `read: #f` The memory cannot be read
- `write: #t` The memory can be written
- `write: #f` The memory is read-only.

close-mmap mm | bigloo procedure

Closes the memory mapped. Returns `#t` on success, `#f` otherwise.

mmap-length mm | bigloo procedure

Returns the length, an exact integer, of the memory mapped.

mmap-read-position mm | bigloo procedure

mmap-read-position-set! mm offset | bigloo procedure

mmap-write-position mm | bigloo procedure

mmap-write-position-set! mm offset | bigloo procedure

Returns and sets the read and write position of a memory mapped memory. The result and the argument are exact integers.

mmap-ref mm offset | bigloo procedure

Reads the character in `mm` at `offset`, an exact long (::elong). This function sets the read position to `offset + 1`.

mmap-set! mm offset char | bigloo procedure

Writes the character `char` in `mm` at `offset`, an exact long (::elong). This function sets the write position to `offset + 1`.

mmap-substring mm start end | bigloo procedure

Returns a newly allocated string made of the characters read from `mm` starting at position `start` and ending at position `end - 1`. If the values `start` and `end` are not ranged in `[0...(mmap-length mm)]`, an error is signaled. The function `mmap-substring` sets the read position to `end`.

mmap-substring-set! mm start str | bigloo procedure

Writes the string `str` to `mm` at position `start`. If the values `start` and `start + (string-length str)` are not ranged in `[0...(mmap-length mm)[`, an error is signaled. The function `mmap-substring` sets the write position to `start + (string-length str)`.

mmap-get-char mm | bigloo procedure

mmap-put-char! mm c | bigloo procedure

mmap-get-string mm len | bigloo procedure

mmap-put-string! mm str | bigloo procedure

These functions get (resp. put) character and strings into a memory mapped area. They increment the read (resp. write) position. An error is signaled if the characters read (resp. writen) outbound the length of the memory mapped.

### 5.2.3 Gzip

port->gzip-port input-port bufsiz | bigloo procedure

This function takes a regular port as input (`input-port`). It constructs a new ports that automatically unzip the read characters.

open-input-gzip-file path [bufsiz] | bigloo procedure

This function opens a gzipped file for input. The file is automatically unzipped when the characters are read. It is equivalent to:

    (let ((p (open-input-port path)))
      (port->gzip-port p))

Gzipped files can also be using the `gzip:` prefix. That is:

    (open-input-gzip-file "a-path.gz")

is equivalent to:

    (open-input-file "gzip:a-path.gz")

gunzip-sendchars input-port output-port | bigloo procedure

Transmit all the characters from the gzipped `input-port` to the `output-port`.
Note that the function `send-chars` can also be used on gzipped input-ports.

gunzip-parse-header input-port | bigloo procedure

Parse the header of `input-port`. Returns `#f` if and only if the port is not gzipped.

### 5.2.4 Tar

tar-read-header [input-port] | bigloo procedure

Reads a tar header from `input-port`. If the input-port does not conform the tar format, an IO exception is raised. On success a tar-header descriptor is returned.

tar-read-block tar-header [input-port] | bigloo procedure

Reads the content of the `tar-header` block.

tar-round-up-to-record-size int | bigloo procedure

Rounds up tar-block sizes.

tar-header-name tar-header | bigloo procedure

tar-header-mode tar-header | bigloo procedure

tar-header-uid tar-header | bigloo procedure

tar-header-gid tar-header | bigloo procedure

tar-header-size tar-header | bigloo procedure

tar-header-mtim tar-header | bigloo procedure

tar-header-checksum tar-header | bigloo procedure

tar-header-type tar-header | bigloo procedure

tar-header-linkname tar-header | bigloo procedure

tar-header-uname tar-header | bigloo procedure

tar-header-gname tar-header | bigloo procedure

tar-header-devmajor tar-header | bigloo procedure

tar-header-devminir tar-header | bigloo procedure

Return various information about `tar-header`.

The following example simulates the Unix command `tar xvfz`:

    (define (untar path)
       (let ((pz (open-input-gzip-port path)))
          (unwind-protect
    	 (let loop ((lst '()))
    	    (let ((h (tar-read-header pz)))
    	       (if (not h)
    		   lst
    		   (case (tar-header-type h)
    		      ((dir)
    		       (let ((path (tar-header-name h)))
    			  (if (make-directory path)
    			      (loop lst)
    			      (error 'untar
    				     "Cannot create directory"
    				     path))))
    		      ((normal)
    		       (let* ((path (tar-header-name h))
    			      (dir (dirname path)))
    			  (when (and (file-exists? dir) (not (directory? dir)))
    			     (delete-file dir))
    			  (unless (file-exists? dir)
    			     (make-directory dir))
    			  (with-output-to-file path
    			     (lambda ()
    				(display (tar-read-block h pz))))
    			  (loop (cons path lst))))
    		      (else
    		       (error 'untar
    			      (format "Illegal file type `~a'"
    				      (tar-header-type h))
    			      (tar-header-name h)))))))
    	 (close-input-port pz))))

untar input-port [:directory (pwd)] [:file #f] | bigloo procedure

Untars the archive whose content is provided by the input port `input-port`.

- If `:file` is provided, `untar` extract the content of the file named `:file` and returns a string. The file name must exactly matches the files of the archive files names. If the file does not exist, `untar` returns `#f`.
- If `:file` is not provided, it untars the whole content, in the directory denoted by `:directory`, which defaults to `(pwd)`. The function `untar`, returns the whole list of created directories and files.

### 5.3 Serialization

string->obj string | bigloo procedure

This function converts a `string` which has been produced by `obj->string` into a Bigloo object.

obj->string object | bigloo procedure

This function converts into a string any Bigloo `object` which does not contain a procedure.

The implementation of the last two functions ensures that for every Bigloo object `obj` (containing no procedure), the expression:

    (equal? obj (string->obj (obj->string obj)))
       => #t

binary-port? obj | bigloo procedure

open-output-binary-file file-name | bigloo procedure

append-output-binary-file file-name | bigloo procedure

open-input-binary-file file-name | bigloo procedure

close-binary-port binary-port | bigloo procedure

flush-binary-port binary-port | bigloo procedure

input-obj binary-port | bigloo procedure

output-obj binary-port obj | bigloo procedure

Bigloo allows Scheme objects to be dumped into, and restored from, files. These operations are performed by the previous functions. The dump and the restore use the two functions `obj->string` and `string->obj`.
It is also possible to use a binary file as a flat character file. This can be done by the means of `output-char`, `input-char`, `output-string`, and `input-string` functions.

input-char binary-port | bigloo procedure

output-char binary-port | bigloo procedure

The function `input-char` reads a single character from a `binary-port`. It returns the read character or the `end-of-file` object. The function `output-char` writes a character into a `binary-port`.

input-string binary-port len | bigloo procedure

output-string binary-port | bigloo procedure

The function `input-string` reads a string from a `binary-port` of maximum length `len`. It returns a newly allocated string whose length is possibly smaller than `len`. The function `output-string` writes a string into a `binary-port`.

input-fill-string! binary-port string | bigloo procedure

Fills a string with characters read from `binary-port` with at most the length of `string`. The function returns the number of filled characters.

register-procedure-serialization! serializer unserializer | bigloo procedure

register-custom-serialization! ident serializer unserializer | bigloo procedure

register-process-serialization! serializer unserializer | bigloo procedure

register-opaque-serialization! serializer unserializer | bigloo procedure

There is no existing portable method to dump and restore a procedure. Thus, if `obj->string` is passed a procedure, it will emit an error message. Sometime, using strict restrictions, it may be convenient to use an ad-hoc framework to serialize and unserialize procedures. User may specify there own procedure serializer and unserializer. This is the role of `register-procedure-serialization!`. The argument `serializer` is a procedure of one argument, converting a procedure into a characters strings. The argument `unserializer` is a procedure of one argument, converting a characters string into a procedure. It belongs to the user to provide correct serializer and unserializer.
Here is an example of procedure serializer and unserializer that may be correct under some Unix platform:

    (module foo
       (extern (macro %sprintf::int (::string ::string ::procedure) "sprintf")))

    (define (string->procedure str)
       (pragma "(obj_t)(strtoul(BSTRING_TO_STRING($1), 0, 16))" str))

    (define (procedure->string proc)
       (let ((item (make-string 10)))
          (%sprintf item "#p%lx" proc)
          item))

    (register-procedure-serialization! procedure->string string->procedure)

    (let ((x 4))
       (let ((obj (cons "toto" (lambda (y) (+ x y)))))
          (let ((nobj (string->obj (obj->string obj))))
    	 (print ((cdr nobj) 5)))))

register-class-serialization! class serializer unserializer | bigloo procedure

Register a serializer/unserializer for a class. Subclasses of `class` inherit this serializer.

    (module class-serialization-example
       (static (class point::object (x (default 10)) (y (default 20)))))

    (register-class-serialization! point
    			       (lambda (o)
    				  (with-access::point o (x y)
    				     (cons x y)))
    			       (lambda (l)
    				  (instantiate::point
    				     (x (car l))
    				     (y (cdr l)))))

    (let ((o (instantiate::point)))
       (let ((s (obj->string (list o o))))
          (print (string-for-read s))
          (let ((l (string->obj s)))
    	 (print l)
    	 (eq? (car l) (cadr l))))) => #t

get-procedure-serialization | bigloo procedure

get-custom-serialization ident | bigloo procedure

get-process-serialization | bigloo procedure

get-opaque-serialization | bigloo procedure

get-class-serialization class | bigloo procedure

Returns the a multiple-values whose first element is the current procedure serializer and whose second element is the current procedure unserializer. If no serializer/unserializer is defined, these procedures return the values `#f #f`.

### 5.4 Bit manipulation

These procedures allow the manipulation of fixnums as bit-fields.

bit-or i1 i2 | bigloo procedure

bit-orelong i1 i2 | bigloo procedure

bit-orllong i1 i2 | bigloo procedure

bit-xor i1 i2 | bigloo procedure

bit-xorelong i1 i2 | bigloo procedure

bit-xorllong i1 i2 | bigloo procedure

bit-and i1 i2 | bigloo procedure

bit-andelong i1 i2 | bigloo procedure

bit-andllong i1 i2 | bigloo procedure

bit-not i | bigloo procedure

bit-notelong i | bigloo procedure

bit-notllong i | bigloo procedure

bit-lsh i1 i2 | bigloo procedure

bit-lshelong i1 i2 | bigloo procedure

bit-lshllong i1 i2 | bigloo procedure

bit-rsh i1 i2 | bigloo procedure

bit-ursh i1 i2 | bigloo procedure

bit-rshelong i1 i2 | bigloo procedure

bit-rshllong i1 i2 | bigloo procedure

    (bit-or 5 3)                           => 7
    (bit-orelong #e5 #e3)                  => #e7
    (bit-xor 5 3)                          => 6
    (bit-andllong #l5 #l3)                 => #l1
    (bit-not 5)                            => -6
    (bit-lsh 5 3)                          => 40
    (bit-rsh 5 1)                          => 2

### 5.5 Weak Pointers

Bigloo may support weak pointers. In order to activate this support, Bigloo must be configured with the `finalization` enabled. That is, the `configure` script must be invoked with the option `--finalization=yes`. When the finalization and weak pointers support is enabled, Bigloo defines the `cond-expand` properties `bigloo-finalizer` and `bigloo-weakptr`. Then a program may test the support with expressions such as:

    (cond-expand
      (bigloo-weakptr <something>)
      (else <something-else>))

Weak pointers are pointers to objects which can be collected by the garbage collector if they are weakly pointed to. An object is weakly pointed to if the only pointers to it are weak pointers. Weakly pointed objects can be collected by the garbage collector, and all the weak pointers to such objects will cease to point to it and point to `#unspecified` instead.

make-weakptr data | bigloo procedure

Creates a weak pointer to `data`.

weakptr? obj | bigloo procedure

Returns `#t` if `obj` is a weak pointer, constructed by `make-weakptr`.

weakptr-data ptr | bigloo procedure

Returns the data object pointed to by `ptr`. If the object has been collected, it returns `#unspecified`.

### 5.6 Hash Tables

Bigloo offers hash tables with support for weak pointers. Here are described functions which define and use them.

make-hashtable [bucket-len] [max-bucket-len] [eq-test] [hashn] [weak-keys] [weak-data] | bigloo procedure

Defines an hash table for which the number of buckets is `bucket-len`. The variable `max-bucket-len` specify when the table should be resized. If provided, these two values have to be exact integers greater or equal to 1. Normally you could ignore `bucket-len` and `max-bucket-len` arguments and call `make-hashtable` with no argument at all. The argument `eqtest` enables the specification of a comparison function. The first argument of this function is the keys contained in the table. The second argument is the searched key. By default hash tables rely on `equal?`. The argument `hashn` specifies an hashing function. It defaults to `get-hashnumber`. The arguments `weak-keys` and `weak-data` specify respectively whether the hash table should use weak pointers to store the keys and/or the data. By default a hash table uses strong pointers for both keys and data. Each optional arguments `bucket-len`, `max-bucket-len`, `eq-test`, `hashn`, `weak-keys`, and `weak-data` can be bound to the Bigloo value `#unspecified` which forces its default.

hashtable? obj | bigloo procedure

Returns `#t` if `obj` is an hash table, constructed by `make-hashtable`.

hashtable-weak-keys? table | bigloo procedure

Returns `#t` if `table` is a hash table with weakly pointed keys.

hashtable-weak-data? table | bigloo procedure

Returns `#t` if `table` is a hash table with weakly pointed data.

hashtable-size table | bigloo procedure

Returns the number of entries contained in `table`. Note that for a weak hash table the size does not guarantee the real size, since keys and/or data can dissapear before the next call to the hash table.

hashtable-contains? table key | bigloo procedure

Returns the boolean `#t` if it exists at least one entry whose key is `key` in `table`. If not entry is found `#f` is returned. Note that for a weak hash table, the fact this procedure returns `#t` does not guarantee that the key (or its associated data) will not dissapear before the next call to the hash table.

hashtable-get table key | bigloo procedure

Returns the entry whose key is `key` in `table`. If no entry is found, or if the key and/or value is weakly pointed to and has dissapeard, `#f` is returned.

hashtable-put! table key obj | bigloo procedure

Puts `obj` in `table` under the key `key`. This function returns the object bound in the table. If there was an object `obj-old` already in the table with the same key as `obj`, this function returns `obj-old`; otherwise it returns `obj`.

hashtable-remove! table key | bigloo procedure

Removes the object associated to `key` from `table`, returning `#t` if such object was bound in table and `#f` otherwise.

hashtable-update! table key update-fun init-value | bigloo procedure

If key is already in table, the new value is calculated by `(update-fun current-value)`. Otherwise the `table` is extended by an entry linking key and `init-value`.

hashtable->vector table | bigloo procedure

hashtable->list table | bigloo procedure

Returns the hash table `table`'s data as a vector or a list. If the hash table is weak, the result will consist only of the data which haven't dissapeared yet and whose keys haven't dissapeared either.

hashtable-key-list table | bigloo procedure

Returns the list of keys used in the `table`. If the hash table is weak, the result will consist only of the keys which haven't dissapeared yet and whose data haven't dissapeared either.

hashtable-map table fun | bigloo procedure

Returns a list whose elements are the result of applying `fun` to each of the keys and elements of `table` (no order is specified). In consequence, `fun` must be a procedure of two arguments. The first one is a key and the second one, an associated object. If the hash table is weak, `fun` will only be mapped on sets of key/datum which haven't dissapeared yet.

hashtable-for-each table fun | bigloo procedure

Applies `fun` to each of the keys and elements of `table` (no order is specified). In consequence, `fun` must be a procedure of two arguments. The first one is a key and the second one, an associated object. If the hash table is weak, `fun` will only be called on sets of key/datum which haven't dissapeared yet.

hashtable-filter! table fun | bigloo procedure

Filter out elements from `table` according to predicate `fun`. If the hash table is weak, `fun` will only be called on sets of key/datum which haven't dissapeared yet.

Here is an example of hash table.

    (define *table* (make-hashtable))

    (hashtable-put! *table* "toto" "tutu")
    (hashtable-put! *table* "tata" "titi")
    (hashtable-put! *table* "titi" 5)
    (hashtable-put! *table* "tutu" 'tutu)
    (hashtable-put! *table* 'foo 'foo)

    (print (hashtable-get *table* "toto"))
       -| "tutu"
    (print (hashtable-get *table* 'foo))
       -| 'foo
    (print (hashtable-get *table* 'bar))
       -| #f

    (hashtable-for-each *table* (lambda (key obj) (print (cons key obj))))
       -| ("toto" . "tutu")
          ("tata" . "titi")
          ("titi" . 5)
          ("tutu" . TUTU)
          (foo . foo)

object-hashnumber object | bigloo generic

This generic function computes a hash number of the instance `object`.
Example:

    (define-method (object-hashnumber pt::point)
       (with-access::point pt (x y)
          (+fx (*fx x 10) y)))

### 5.7 System programming

### 5.7.1 Operating System interface

register-exit-function! proc | bigloo procedure

Register `proc` as an exit functions. `Proc` is a procedure accepting of one argument. This argument is the numerical value which is the status of the exit call. The registered functions are called when the execution ends.

exit int | bigloo procedure

Apply all the registered exit functions then stops an execution, returning the integer `int`.

signal n proc | bigloo procedure

Provides a signal handler for the operating system dependent signal `n`. `proc` is a procedure of one argument.

get-signal-handler n | bigloo procedure

Returns the current handler associated with signal `n` or `#f` if no handler is installed.

system . strings | bigloo procedure

Append all the arguments `strings` and invoke the native host `system` command on that new string which returns an integer.

system->string . strings | bigloo procedure

Append all the arguments `strings` and invoke the native host `system` command on that new string. If the command completes, `system->string` returns a string made of the output of the command.

getenv string | bigloo procedure

Returns the string value of the Unix shell's `string` variable. If no such variable is bound, `getenv` returns `#f`.

putenv string val | bigloo procedure

Adds or modifies the global environment variable `string` so that it is bound to `val` after the call. This facility is not supported by all back-end. In particular, the JVM back-end does not support it.

date | bigloo procedure

Returns the current date in a `string`. See also Date.

sleep micros | bigloo procedure

Sleeps for a delay during at least `micros` microseconds.

command-line | bigloo procedure

Returns a list of strings which are the Unix command line arguments.

executable-name | bigloo procedure

Returns the name of the running executable.

os-class | bigloo procedure

Gives the OS class (e.g. `unix`).

os-name | bigloo procedure

Gives the OS name (e.g. `Linux`).

os-arch | bigloo procedure

Gives the host architecture (e.g. `i386`).

os-version | bigloo procedure

Gives the operating system version (e.g. `RedHat 2.0.27`).

os-tmp | bigloo procedure

Gives the regular temporary directory (e.g. `/tmp`).

file-separator | bigloo procedure

Gives the operating system file separator (e.g. `#\/`).

path-separator | bigloo procedure

Gives the operating system file path separator (e.g.`#\:`).

For additional functions (such as `directory->list`) see Input and Output.

unix-path->list | bigloo procedure

Converts a Unix path to a Bigloo list of strings.

    (unix-path->list ".")           => (".")
    (unix-path->list ".:/usr/bin")  => ("." "/usr/bin")

hostname | bigloo procedure

Returns the fully qualified name of the current host.

time thunk | bigloo procedure

Evaluates the `thunk` and returns four values: the result of calling `thunk`, the actual execution time, the system time, and the user time.

    (multiple-value-bind (res rtime stime utime)
      (time (lambda () (fib 35)))
      (print "real: " rtime " sys: " stime " user: " stime))

### 5.7.2 Files

See Input and Output for file and directory handling. This section only deals with name handling. Four procedures exist to manipulate Unix filenames.

basename string | bigloo procedure

Returns a copy of `string` where the longest prefix ending in `/` is deleted if any existed.

prefix string | bigloo procedure

Returns a copy of `string` where the suffix starting by the char `#\.` is deleted. If no prefix is found, the result of `prefix` is a copy of `string`. For instance:

    (prefix "foo.scm")
       => "foo"
    (prefix "./foo.scm")
       => "./foo"
    (prefix "foo.tar.gz")
       => "foo.tar"

suffix string | bigloo procedure

Returns a new string which is the suffix of `string`. If no suffix is found, this function returns an empty string. For instance,

    (suffix "foo.scm")
       => "scm"
    (suffix "./foo.scm")
       => "scm"
    (suffix "foo.tar.gz")
       => "gz"

dirname string | bigloo procedure

Returns a new string which is the directory component of `string`. For instance:

    (dirname "abc/def/ghi")
       => "abc/def"
    (dirname "abc")
       =>  "."
    (dirname "abc/")
       => "abc"
    (dirname "/abc")
       => "/"

pwd | bigloo procedure

Returns the current working directory.

chdir dir-name | bigloo procedure

Changes the current directory to `dir-name`. On success, `chdir` returns `#t`. On failure it returns `#f`.

make-file-name dir-name name | bigloo procedure

Make an absolute file-name from a directory name `dir-name` and a relative name `name`.

make-file-path dir-name name . names | bigloo procedure

Make an absolute file-name from a directory name `dir-name` and a relative name `name`s.

file-name->list name | bigloo procedure

Explodes a file name into a list.

    (file-name->list "/etc/passwd")
       => '("" "etc" "passwd")
    (file-name->list "etc/passwd")
       => '("etc" "passwd")

file-name-canonicalize name | bigloo procedure

file-name-canonicalize! name | bigloo procedure

file-name-unix-canonicalize name | bigloo procedure

file-name-unix-canonicalize! name | bigloo procedure

Canonicalizes a file name. If the file name is malformed this function raises an `&io-malformed-url-error` exception.
In addition to handling `..` directory name, the function `file-name-unix-canonicalize` also handles the `~` character.

    (file-name-canonicalize "/etc/passwd")
       => "/etc/passwd"
    (file-name-canonicalize "/etc/../tmp/passwd")
       => "/tmp/passwd"
    (file-name-canonicalize "~/passwd")
       => "~/passwd"
    (file-name-unix-canonicalize "~/passwd")
       => "/home/a-user/passwd"
    (file-name-unix-canonicalize "~foo/passwd")
       => "/home/foo/passwd"

relative-file-name name base | bigloo procedure

Builds a file name relative to `base`.

    (find-file/path "/etc/passwd" "/etc"
       => "passwd"

find-file/path name path | bigloo procedure

Search, in sequence, in the directory list `path` for the file `name`. If `name` is an absolute name, then `path` is not used to find the file. If `name` is a relative name, the function `make-file-name` is used to build absolute name from `name` and the directories in `path`. The current path is not included automatically in the list of `path`. In consequence, to check the current directory one may add `"."` to the `path` list. On success, the absolute file name is returned. On failure, `#f` is returned. Example:

    (find-file/path "/etc/passwd" '("/toto" "/titi"))
       => "/etc/passwd"
    (find-file/path "passwd" '("/toto" "/etc"))
       => "/etc/passwd"
    (find-file/path "pass-wd" '("." "/etc"))
       => #f

make-static-library-name name | bigloo procedure

Make a static library name from `name` by adding the static library regular suffix.

make-shared-library-name name | bigloo procedure

Make a shared library name from `name` by adding the shared library regular suffix.

file-exists? string | bigloo procedure

This procedure returns `#t` if the file `string` exists. Otherwise it returns `#f`.

file-gzip? string | bigloo procedure

This procedure returns `#t` if and only if the file `string` exists and can be unzip by Bigloo. Otherwise it returns `#f`.

delete-file string | bigloo procedure

Deletes the file named `string`. The result of this procedure is `#t` is the operation succeeded. The result is `#f` otherwise.

rename-file string1 string2 | bigloo procedure

Renames the file `string1` as `string2`. The two files have to be located on the same file system. If the renaming succeeds, the result is `#t`, otherwise it is `#f`.

copy-file string1 string2 | bigloo procedure

Copies the file `string1` into `string2`. If the copy succeeds, the result is `#t`, otherwise it is `#f`.

directory? string | bigloo procedure

This procedure returns `#t` if the file `string` exists and is a directory. Otherwise it returns `#f`.

make-directory string | bigloo procedure

Creates a new directory named `string`. It returns `#t` if the directory was created. It returns `#f` otherwise.

make-directories string | bigloo procedure

Creates a new directory named `string`, including any necessary but nonexistent parent directories. It returns `#t` if the directory was created. It returns `#f` otherwise. Note that if this operation fails it may have succeeded in creating some of the necessary parent directories.

delete-directory string | bigloo procedure

Deletes the directory named `string`. The directory must be empty in order to be deleted. The result of this procedure is unspecified.

directory->list string | bigloo procedure

directory->path-list string | bigloo procedure

If file `string` exists and is a directory, the function `directory->list` returns the list of files in `string`. The function `directory->path-list` returns a list of files whose dirname is `string`.

file-modification-time string | bigloo procedure

The date (in second) of the last modification for file `string`. The number of seconds is represented by a value that may be converted into a date by the means of `seconds->date` (see Date).

file-size string | bigloo procedure

Returns the size (in bytes) for file `string`. The return type is `long`. If an full-sized integer is needed, one may write:

    (let ((sz::llong (file-size <PATH>)))
     ...)

    On error, -1 is returned.

file-uid string | bigloo procedure

file-gid string | bigloo procedure

The functions return the user id (an integer) and group id (an integer) for file `string`. On error, `-1` is returned.

file-mode string | bigloo procedure

Returns the file access mode (an integer). On error `-1` is returned.

chmod string [option] | bigloo procedure

Change the access mode of the file named `string`. The `option` must be either a list of the following symbols `read`, `write` and `execute` or an integer. If the operation succeeds, `chmod` returns `#t`. It returns `#f` otherwise. The argument `option` can also be an integer that represents the native file permission. Example:

    (chmod (make-file-name (getenv "HOME") ".bigloorc") 'read 'write)
    (chmod (make-file-name (getenv "HOME") ".bigloorc") #o777)

### 5.7.3 Process support

Bigloo provides access to Unix-like processes as first class objects. The implementation and this documentation are to a great extent copies of the STk [Gallesio95] process support. Basically, a process contains four informations: the standard Unix process identification (aka PID) and the three standard files of the process.

run-process command arg... | bigloo procedure

`run-process` creates a new process and run the executable specified in `command`. The `arg` correspond to the command line arguments. When is process completes its execution, non pipe associated ports are automatically closed. Pipe associated ports have to be explicitly closed by the program. The following values of `p` have a special meaning:

- `input:` permits to redirect the standard input file of the process. Redirection can come from a file or from a pipe. To redirect the standard input from a file, the name of this file must be specified after `input:`. Use the special keyword `pipe:` to redirect the standard input from a pipe.
- `output:` permits to redirect the standard output file of the process. Redirection can go to a file or to a pipe. To redirect the standard output to a file, the name of this file must be specified after `output:`. Use the special keyword `pipe:` to redirect the standard output to a pipe.
- `error:` permits to redirect the standard error file of the process. Redirection can go to a file or to a pipe. To redirect the standard error to a file, the name of this file must be specified after `error:`. Use the special keyword `pipe:` to redirect the standard error to a pipe.
- `wait:` must be followed by a boolean value. This value specifies if the process must be ran asynchronously or not. By default, the process is run asynchronously (i.e. `wait:` if `#f`).
- `host:` must be followed by a string. This string represents the name of the machine on which the `command` must be executed. This option uses the external command `rsh`. The shell variable `PATH` must be correctly set for accessing it without specifying its absolute path.
- `fork:` must be followed by a boolean value. This value specifies if the process must substitute the current execution. That is, if the value is `#t` a new process is spawned otherwise, the current execution is stopped and replaced by the execution of `command`. It defaults to `#t`.
- `env:` must be followed by a string of the form ``var`=`val``. This will bound an environment variable in the spawned process. A `run-process` command may contain several `env:` arguments. The current variables of the current process are also passed to the new process.

The following example launches a process which execute the Unix command `ls` with the arguments `-l` and `/bin`. The lines printed by this command are stored in the file `tmp/X`.

    (run-process "ls" "-l" "/bin" output: "/tmp/X")

The same example with a pipe for output:

    (let* ((proc (run-process "ls" "-l" "/bin" output: pipe:))
           (port (process-output-port proc)))
       (let loop ((line (read-line port)))
          (if (eof-object? line)
              (close-input-port port)
              (begin
                 (print line)
                 (loop (read-line port))))))

One should note that the same program can be written with explicit process handling but making use of the `|` notation for `open-input-file`.

    (let ((port (open-input-file "| ls -l /bin")))
       (let loop ((line (read-line port)))
          (if (eof-object? line)
              (close-input-port port)
              (begin
                 (print line)
                 (loop (read-line port))))))

Both input and output ports can be piped:

    (let* ((proc (run-process "/usr/bin/dc" output: pipe: input: pipe:))
           (inport (process-input-port proc))
           (port (process-output-port proc)))
       (fprint inport "16 o")
       (fprint inport "16 i")
       (fprint inport "10")
       (fprint inport "10")
       (fprint inport "+ p")
       (flush-output-port inport)
       (let loop ((line (read-line port)))
          (if (eof-object? line)
    	  (close-input-port port)
    	  (begin
    	     (print line)
    	     (loop (read-line port))))))   -| 20

Note: The call to `flush-output-port` is mandatory in order to get the `dc` process to get its input characters.
Note: Thanks to Todd Dukes for the example and the suggestion of including it this documentation.

process? obj | bigloo procedure

Returns `#t` if `obj` is a process, otherwise returns `#f`.

process-alive? process | bigloo procedure

Returns `#t` if `process` is currently running, otherwise returns `#f`.

close-process-ports command arg... | bigloo procedure

Close the three ports associated with a process. In general the ports should not be closed before the process is terminated.

process-pid process | bigloo procedure

Returns an integer value which represents the Unix identification (PID) of the `process`.

process-input-port process | bigloo procedure

process-output-port process | bigloo procedure

process-error-port process | bigloo procedure

Return the file port associated to the standard input, output and error of `process` otherwise returns `#f`. Note that the returned port is opened for reading when calling `process-output-port` or `process-error-port`. It is opened for writing when calling `process-input-port`.

process-wait process | bigloo procedure

This function stops the current process until `process` completion. This function returns `#f` when `process` is already terminated. It returns `#t` otherwise.

process-exit-status process | bigloo procedure

This function returns the exit status of `process` if it is has finished its execution. It returns `#f` otherwise.

process-send-signal process s | bigloo procedure

Sends the signal whose integer value is `s` to `process`. Value of `s` is system dependent. The result of `process-send-signal` is undefined.

process-kill process | bigloo procedure

This function brutally kills `process`. The result of `process-kill` is undefined.

process-stop process | bigloo procedure

process-continue process | bigloo procedure

Those procedures are only available on systems that support job control. The function `process-stop` stops the execution of `process` and `process-continue` resumes its execution.

process-list | bigloo procedure

This function returns the list of processes which are currently running (i.e. alive).

### 5.7.4 Socket support

Bigloo defines sockets, on systems that support them, as first class objects. Sockets permits processes to communicate even if they are on different machines. Sockets are useful for creating client-server applications. The implementation and this documentation are, to a great extent copies of the STk [Gallesio95] socket support.

make-client-socket hostname port-number #!key (buffer #t) (timeout 0) | bigloo procedure

`make-client-socket` returns a new socket object. This socket establishes a link between the running application listening on port `port-number` of `hostname`. If keyword argument `buffer` is `#f` then the input port associated with the socket is unbuffered. This is useful for socket clients connected to servers that do not emit #\Newline character after emissions. If optional argument `buffered` is missing or is not to `#f` the input port uses a buffer. If the optional argument `timeout` is missing or is `0`, the execution blocks until the connection is established. If the `timeout` is provided, the execution unblocks after `timeout` microseconds unless the connection is established.
If the connection cannot be established, an `&io-error` is raised (see Errors and Assertions).
When a socket is used in unbufferized mode the characters available on the input port must be read exclusively with `read-char` or `read-line`. It is forbidden to use `read` or any regular grammar. This limitation is imposed by Rgc (see Regular Parsing) that intrinsicly associates buffers with regular grammars. If the current Rgc implementation is improved on the coming version this restriction will be eliminated.
Example:

    ;; open a client socket on port 80:
    (make-client-socket "www.inria.fr" 80)
    ;; open an unbufferized connection
    (make-client-socket "www.inria.fr" 80 :buffer #f)

socket? obj | bigloo procedure

socket-server? obj | bigloo procedure

socket-client? obj | bigloo procedure

Returns `#t` if `obj` is a socket, a socket server a socket client. Otherwise returns `#f`. Socket servers and socket clients are sockets.

socket-hostname socket | bigloo procedure

Returns a string which contains the name of the distant host attached to `socket`. If `socket` has been created with `make-client-socket` this procedure returns the official name of the distant machine used for connection. If `socket` has been created with `make-server-socket`, this function returns the official name of the client connected to the socket. If no client has used yet the socket, this function returns `#f`.

socket-host-address socket | bigloo procedure

Returns a string which contains the IP number of the distant host attached to `socket`. If `socket` has been created with `make-client-socket` this procedure returns the IP number of the distant machine used for connection. If `socket` has been created with `make-server-socket`, this function returns the address of the client connected to the socket. If no client has used yet the socket, this function returns `#f`.

socket-local-address socket | bigloo procedure

Returns a string which contains the IP number of the local host attached to `socket`.

socket-port-number socket | bigloo procedure

Returns the integer number of the port used for `socket`.

socket-input socket | bigloo procedure

socket-output socket | bigloo procedure

Returns the file port associated for reading or writing with the program connected with `socket`. If no connection has already been established, these functions return `#f`.
The following example shows how to make a client socket. Here we create a socket on port 13 of the machine ```kaolin.unice.fr`''1:

    (let ((s (make-client-socket "kaolin.unice.fr" 13)))
      (print "Time is: " (read-line (socket-input s)))
      (socket-shutdown  s))

make-server-socket #!key (name #f) #!optional (port 0) | bigloo procedure

`make-server-socket` returns a new socket object. The socket will be listening on the network interface `name`, either on the specified `port`, or on a port chosen by the system (usually the first port available on the network interface). The `name` can be an IP number as a string, or a host name, whose first IP address will be used (as returned by the name server lookup).

socket-accept socket #!key (buffer #t) (errp #t) | bigloo procedure

`socket-accept` waits for a client connection on the given `socket`. It returns a `client-socket`. If no client is already waiting for a connection, this procedure blocks its caller; otherwise, the first connection request on the queue of pending connections is connected to `socket`. This procedure must be called on a server socket created with `make-server-socket`. If keyword argument `buffer` is `#f` then the input port associated with the socket is unbuffered. This is useful for socket clients connected to servers that do not emit #\Newline character after emissions. If keyword argument `buffer` is missing or is not to `#f` the input port uses a buffer. The keyword argument `errp` is a boolean. The value `#t` means that if an error is raised it is signaled. Otherwise, it is omitted.
Note: When a socket is used in unbufferized mode the characters available on the input port must be read exclusively with `read-char` or `read-line`. It is forbidden to use `read` or any regular grammar. This limitation is imposed by Rgc (see Regular Parsing) that intrinsicly associate buffers with regular grammars. If the current Rgc implementation is improved on the coming version this restriction will be suppressed.
The following exemple is a simple server which waits for a connection on the port 12342. Once the connection with the distant program is established, we read a line on the input port associated to the socket and we write the length of this line on its output port.

    (let* ((s (make-server-socket 1234))
           (s2 (socket-accept s)))
      (let ((l (read-line (socket-input s2))))
        (fprint (socket-output s2) "Length is: " (string-length l))
        (flush-output-port (socket-output s2)))
      (socket-close s2)
      (socket-shutdown s))

socket-close socket | bigloo procedure

The function `socket-close` closes the connection established with a `socket-client`.

socket-shutdown socket #!optional (close #t) | bigloo procedure

`Socket-shutdown` shutdowns the connection associated to `socket`. `Close` is a boolean; it indicates if the socket must be closed or not, when the connection is destroyed. Closing the socket forbids further connections on the same port with the `socket-accept` procedure. Omitting a value for `close` implies the closing of socket. The result of `socket-shutdown` is undefined.

socket-down? socket | bigloo procedure

Returns `#t` if `socket` has been previously closed with `socket-shutdown`. It returns `#f` otherwise.

Here is another example of making use of sockets:

    (define s1 (make-server-socket))
    (define s2 #unspecified)

    (dynamic-wind
       ;; Init: Launch an xterm with telnet running
       ;; on the s listening port and connect
       (lambda ()
          (run-process "/usr/X11R6/bin/xterm" "-display" ":0" "-e" "telnet" "localhost"
    		   (number->string (socket-port-number s1)))
          (set! s2 (socket-accept s1))
          (display #"\nWelcome on the socket REPL.\n\n> " (socket-output s2))
          (flush-output-port (socket-output s2)))

       ;; Action: A toplevel like loop
       (lambda ()
          (let loop ()
    	 (let ((obj (eval (read (socket-input s2)))))
    	    (fprint (socket-output s2) "; Result: " obj)
    	    (display "> " (socket-output s2))
    	    (flush-output-port (socket-output s2))
    	    (loop))))

       ;; Termination: We go here when
       ;;     -a: an error occurs
       ;;     -b: connection is closed
       (lambda ()
          (print #"Shutdown ......\n")
          (socket-close s2)
          (socket-shutdown s1)))

Here is a second example that uses sockets. It implements a client-server architecture and it uses unbufferized (see `socket-accept`) input ports. First, here is the code of the client:

    (module client)

    (let* ((s (make-client-socket "localhost" 8080 #f))
           (p (socket-output s)))
       (display "string" p)
       (newline p)
       (display "abc" p)
       (flush-output-port p)
       (let loop ()
          (loop)))

Then, here is the code of the server:

    (module server)

    (let* ((s (make-server-socket 8080))
           (s2 (socket-accept s #f)))
       (let ((pin (socket-input s2)))
          (let loop ()
             (display (read-char pin))
             (flush-output-port (current-output-port))
             (loop))))

At, to conclude here the source code for a server waiting for multiple consecutive connections:

    (define (main argv)
       (let ((n (if (pair? (cdr argv))
                    (string->integer (cadr argv))
                    10))
    	 (s (make-server-socket)))
          (print "s: " s)
          (let loop ((i 0))
             (if (<fx i n)
                 (let ((s2 (socket-accept s)))
    		(print "i: " i " " s2)
    		(print (read-line (socket-input s2)))
    		(socket-close s2)
                    (loop (+fx i 1)))
    	     (socket-shutdown s)))))

host hostname | bigloo procedure

hostinfo hostname | bigloo procedure

Returns the IP number of `hostname`. When `hostname` is not found, the `io-unknown-host-error` exception is raided (see Errors and Assertions).
The function `hostinfo` possibly returns more information about the host. It returns an association list made out the information about the host. This list might contain a `name` entry, an `addresses` entry, and a `aliases` entry.
Some back-ends (e.g., the C back-end) implements DNS caching. This may dramatically improve the performance of intensive networking applications. DNS caching can be control by the means of two parameters: `bigloo-dns-enable-cache` and `bigloo-dns-cache-validity-timeout` (see Parameters).

### 5.7.5 SSL

Bigloo allows access to SSL sockets, certificates and private keys, in order to build secure encrypted and/or signed communications.

#### 5.7.5.1 SSL Sockets

Bigloo defines SSL sockets, on systems that support them, as first class objects. SSL Sockets permits processes to communicate even if they are on different machines securely via encrypted connections. SSL Sockets are useful for creating secure client-server applications.

make-ssl-client-socket hostname port-number #!key (buffer #t) (timeout 0) (protocol 'sslv23) (cert #f) (pkey #f) (CAs '()) (accepted-certs #f) | SSL library procedure

`make-ssl-client-socket` returns a new client socket object. This object satisfies the `socket?` predicate (see Socket) can be used in any context where a socket created by `make-client-socket` can be used.
A SSL client socket establishes a link between the running application (client) and a remote application (server) listening on port `port-number` of `hostname`. If optional argument `buffer` is `#f` then the input port associated with the socket is unbuffered. This is useful for socket clients connected to servers that do not emit #\Newline character after emissions. If optional argument `buffer` is not to `#f` the input port uses a buffer. If the optional argument `timeout` is `0`, the execution blocks until the connection is established. If the `timeout` is provided, the execution unblocks after `timeout` microseconds unless the connection is established. If the `protocol` option argument is given, it specifies the encryption protocol. Accepted values are `'sslv2`, `'sslv3`, `'sslv23` (alias `'ssl`), `'tls` (alias `'tlsv1`) or `'dtls` (alias `'dtlsv1`). The default value is `'sslv23`.
The SSL socket will sign the connection using the optional arguments `cert` (for the certificate) and `pkey` (for the private key). The certificate `cert` must be of type `certificate`, and the private key `pkey` must be of type `private-key`. If any of those two arguments is given, they must both be given. If those optional arguments are missing the connection will be encrypted but not signed from the client side.
The `CAs` optional argument specifies the list of certificates to trust as CA (Certificate Authority) for the connection. It must be a list of values of type `certificate`. If the list is empty, the default list of trusted CA is used (set by the system). Note that giving a list of trusted certificates turns on the peer (server) certificate validation: an `&io-error` will be raised if the peer (server) certificate is not signed directly or indirectly by one of the certificates in `CAs`.
The `accepted-certs` optional argument gives a list of certificate objects (of type `certificate`) which are accepted as peer (server) certificate. If `accepted-certs` is `#f` then every peer (server) certificate is accepted (aside from eventual certificate validation). If `accepted-certs` is a list, the peer (server) certificate must match one of the given certificates. Otherwise, an `&io-error` will be raised.
If the connection cannot be established, an `&io-error` is raised (see Errors and Assertions).
When a socket is used in unbufferized mode the characters available on the input port must be read exclusively with `read-char` or `read-line`. It is forbidden to use `read` or any regular grammar. This limitation is imposed by Rgc (see Regular Parsing) that intrinsicly associates buffers with regular grammars. If the current Rgc implementation is improved on the coming version this restriction will be eliminated.
The function `make-ssl-client-socket` is defined in the SSL library. A module that needs this facility must then use a `library` clause (see Modules). The SSL library can also be loaded from the interpreter using the `library-load` function (see Bigloo Libraries).

    (module imap
       (library ssl)
       (main main))

    (let* ((s (make-ssl-client-socket "localhost" 993))
           (p (socket-output s)))
       (display "string" p)
       (newline p)
       (display "abc" p)
       (flush-output-port p)
       (let loop ()
          (loop)))

client-socket-use-ssl! socket #!key (protocol 'sslv23) (cert #f) (pkey #f) (CAs '()) (accepted-certs #f) | SSL library procedure

Returns an SSL socket built from a socket obtained by `make-client-socket` (see Socket). Depending on the implementation and back-end the returned socket may or may not be `eq?` to `socket`.

make-ssl-server-socket #!key (port 0) (name #f) (protocol 'sslv23) (cert #f) (pkey #f) (CAs '()) (accepted-certs #f) | SSL library procedure

`make-ssl-server-socket` returns a new server socket object which satisfies the `socket?` predicate and which can be used in any context where a socket created by `make-server-socket` can be used (see Socket).
A SSL server socket opens the port `port` on the current host `name` (the server), and allows remote applications (clients) to connect to it. listening on port `port-number` of `hostname`. If the optional argument `port` is not given or is `0`, the server socket will use the first availailable port number. If the optional argument `name` is given, the server socket will be bound to the network interface representing the given host name. If it is `#f` (the default) the socket will be bound on every local network interface. If the `protocol` option argument is given, it specifies the encryption protocol. Accepted values are `'sslv2`, `'sslv3`, `'sslv23` (alias `'ssl`), `'tls` (alias `'tlsv1`) or `'dtls` (alias `'dtlsv1`). The default value is `'sslv23`.
The SSL socket will sign the connection using the optional arguments `cert` (for the certificate) and `pkey` (for the private key). The certificate `cert` must be of type `certificate`, and the private key `pkey` must be of type `private-key`. If any of those two arguments is given, they must both be given. If those optional arguments are missing the connection will be encrypted but not signed from the server side, which means the peer (client) will have to provide a certificate/private key pair to encrypt the connection, and that seldom happens. Typical SSL servers provide their certificate and private key.
Note that since the peer (client) certificate is only known when we are accepting a client socket (with `socket-accept`) the `CAs` and `accepted-certs` optional arguments are only checked during the accept operation of a server socket.
The `CAs` optional argument specifies the list of certificates to trust as CA (Certificate Authority) for the connection. It must be a list of values of type `certificate`. If the list is empty, the default list of trusted CA is used (set by the system). Note that giving a list of trusted certificates turns on the peer (client) certificate validation: an `&io-error` will be raised if the peer (client) certificate is not signed directly or indirectly by one of the certificates in `CAs` when accepting the client socket.
The `accepted-certs` optional argument gives a list of certificate objects (of type `certificate`) which are accepted as peer (client) certificate. If `accepted-certs` is `#f` then every peer (client) certificate is accepted (aside from eventual certificate validation). If `accepted-certs` is a list, the peer (client) certificate must match one of the given certificates. Otherwise, an `&io-error` will be raised when accepting the client socket.
If the connection cannot be established, an `&io-error` is raised (see Errors and Assertions).
The function `make-ssl-server-socket` is defined in the SSL library. A module that needs this facility must then use a `library` clause (see Modules). The SSL library can also be loaded from the interpreter using the `library-load` function (see Bigloo Libraries).

    (module secure-echo
       (library ssl))

    (let* ((cert (read-certificate "/etc/ssl/my_cert.crt"))
           (pkey (read-private-key "/etc/ssl/my_key.pkey"))
           (cas (read-pem-file "/etc/ssl/ca.cert"))
           (s (make-ssl-server-socket 1055 :CAs cas :cert cert :pkey pkey))
           (cs (socket-accept s))
           (ip (socket-input cs))
           (op (socket-output cs)))
       (let loop ((e (read i)))
          (when (not (eof-object? e))
             (write e o)
             (loop (read i))))
       (socket-close s))

#### 5.7.5.2 Certificates

read-certificate file | SSL library procedure

Reads an X509 certificate stored in PEM format in the given `file` name. If the file cannot be read, it raises an `&io-error` condition. Otherwise the certificate is returned.

read-pem-file file | SSL library procedure

Reads a list of X509 certificate stored in PEM format in the given `file` name. If the file cannot be read, it raises an `&io-error` condition. Otherwise the list of certificate contained in the file is returned.

certificate? obj | SSL library procedure

Returns `#t` if `obj` is an SSL certificate. Otherwise returns `#f`.

certificate-subject cert | SSL library procedure

Returns the CommonName (CN) part of the subject of the given certificate.

certificate-issuer cert | SSL library procedure

Returns the CommonName (CN) part of the issuer of the given certificate.

#### 5.7.5.3 Private Keys

read-private-key file | SSL library procedure

Reads a private key stored in PEM format in the given `file` name. If the file cannot be read, it raises an `&io-error` condition. Otherwise the private key is returned.

private-key? obj | SSL library procedure

Returns `#t` if `obj` is an SSL private key. Otherwise returns `#f`.

### 5.8 Date

date? obj | bigloo procedure

Returns `#t` if and only if `obj` is a date as returned by `make-date`, `current-date`, or `seconds->date`. It returns `#f` otherwise.

make-date #!key (sec 0) (min 0) (hour 0) (day 0) (month 0) (year 1970) timezone (dst -1) | bigloo procedure

Creates a `date` object from the integer values passed as argument.
The argument `timezone`, if provided, is expressed in minute.
Example:

    (write (make-date :sec 0 :min 22 :hour 17 :day 5 :month 2 :year 2003 :dst 0))
      -| #<date:Wed Feb  5 17:22:00 2003>

The argument `dst` is either `-1` when the information is not available, `0` when daylight saving is disabled, `1` when daylight saving is enabled.

date-copy date #!key sec min hour day month year | bigloo procedure

Creates a new date from the argument `date`.
Example:

    (date-copy (current-date) 1 0 0)

current-date | bigloo procedure

Returns a `date` object representing the current date.

current-seconds | bigloo procedure

Returns an `elong` integer representing the current date expressed in seconds.

date->seconds | bigloo procedure

seconds->date | bigloo procedure

Convert from `date` and `elong`.

date->string date | bigloo procedure

date->utc-string date | bigloo procedure

seconds->string elong | bigloo procedure

seconds->utc-string elong | bigloo procedure

Construct a textual representation of the date passed in argument

date-second date | bigloo procedure

Returns the number of seconds of a date, in the range `0...59`.

date-minute date | bigloo procedure

Returns the minute of a date, in the range `0...59`.

date-hour date | bigloo procedure

Returns the hour of a date, in the range `0...23`.

date-day date | bigloo procedure

Returns the day of a date, in the range `1...31`.

date-wday date | bigloo procedure

date-week-day date | bigloo procedure

Returns the week day of a date, in the range `1...7`.

date-yday date | bigloo procedure

date-year-day date | bigloo procedure

Returns the year day of a date, in the range `1...366`.

date-month date | bigloo procedure

Returns the month of a date, in the range `1...12`.

date-year date | bigloo procedure

Returns the year of a date.

date-timezone date | bigloo procedure

Returns the timezone of a date.

date-is-dst date | bigloo procedure

Returns `-1` if the information is not available, `0` is the date does not contain daylight saving adjustment, `1` if it contains a daylight saving adjustment.

integer->second | bigloo procedure

Converts a Bigloo fixnum integer into a second number.

day-seconds | bigloo procedure

Returns the number of seconds contained in one day.

day-name int | bigloo procedure

day-aname int | bigloo procedure

Return the name and the abbreviated name of a week day.

month-name int | bigloo procedure

month-aname int | bigloo procedure

Return the name and the abbreviated name of a month.

date-month-length date | bigloo procedure

Return the length of the month of `date`.

leap-year? int | bigloo procedure

Returns `#t` if and only if the year `int` is a leap year. Returns `#f` otherwise.

rfc2822-date->date string | bigloo procedure

rfc2822-parse-date input-port | bigloo procedure

Parses RFC2822 string representing a date. These functions produce a Bigloo date object.

date->rfc2822-date date | bigloo procedure

Converts a Bigloo date into a string representation compliant with the RFC2822 format.

### 5.9 Digest

base64-encode string [padding 64] | bigloo procedure

base64-decode string | bigloo procedure

Encodes (respec. decodes) a string into a base64 representation.

base64-encode-port input-port output-port [padding 64] | bigloo procedure

base64-decode-port input-port output-port | bigloo procedure

Encodes (respec. decodes) an input port into a base64 representation.

pem-read-file file-name | bigloo procedure

pem-decode-port input-port output-port | bigloo procedure

Reads a PEM (Privacy Enhanced Mail) base64 encoded file.

md5sum obj | bigloo procedure

md5sum-string string | bigloo procedure

md5sum-mmap mmap | bigloo procedure

md5sum-file string | bigloo procedure

md5sum-port input-port | bigloo procedure

Computes MD5 message digest.
The function `md5sum` dispatches over its argument and invokes the ad-hoc function. That is, it invokes `md5sum-string` if its argument is a string, `md5sum-mmap` if it is a mmap, `md5sum-port` if its argument is an input port.

hmac-md5sum-string key string | bigloo procedure

Computes the Hmac MD5 authentication:

    (hmac-md5sum-string (make-string 16 #a011) "Hi There")
      => "9294727a3638bb1c13f48ef8158bfc9d"

cram-md5sum-string user key string | bigloo procedure

Challenge-Response Authentication Mechanism as specified in RFC 2195.
The function `cram-md5sum-string` assumes that data is base64 encoded. The result is also base64 encoded.

1: Port 13 is generally used for testing: making a connection to it permits to know the distant system's idea of the time of day.
2: Under Unix, you can simply connect to listening socket with the `telnet` command. With the given example, this can be achived by typing the following command in a window shell: `$ telnet localhost 1234`

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