;;;; optargs.scm -- support for optional arguments
;;;;
;;;; Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
-;;;;
+;;;;
;;;; This program is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 2, or (at your option)
;;;; any later version.
-;;;;
+;;;;
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;;; GNU General Public License for more details.
-;;;;
+;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with this software; see the file COPYING. If not, write to
;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
;;;; Boston, MA 02111-1307 USA
-;;;;
+;;;;
+;;;; As a special exception, the Free Software Foundation gives permission
+;;;; for additional uses of the text contained in its release of GUILE.
+;;;;
+;;;; The exception is that, if you link the GUILE library with other files
+;;;; to produce an executable, this does not by itself cause the
+;;;; resulting executable to be covered by the GNU General Public License.
+;;;; Your use of that executable is in no way restricted on account of
+;;;; linking the GUILE library code into it.
+;;;;
+;;;; This exception does not however invalidate any other reasons why
+;;;; the executable file might be covered by the GNU General Public License.
+;;;;
+;;;; This exception applies only to the code released by the
+;;;; Free Software Foundation under the name GUILE. If you copy
+;;;; code from other Free Software Foundation releases into a copy of
+;;;; GUILE, as the General Public License permits, the exception does
+;;;; not apply to the code that you add in this way. To avoid misleading
+;;;; anyone as to the status of such modified files, you must delete
+;;;; this exception notice from them.
+;;;;
+;;;; If you write modifications of your own for GUILE, it is your choice
+;;;; whether to permit this exception to apply to your modifications.
+;;;; If you do not wish that, delete this exception notice.
+;;;;
;;;; Contributed by Maciej Stachowiak <mstachow@alum.mit.edu>
\f
-(define-module (ice-9 optargs))
-
-\f
+;;; Commentary:
;;; {Optional Arguments}
;;;
;;; a convenient and attractive syntax.
;;;
;;; exported macros are:
-;;; bound?
;;; let-optional
;;; let-optional*
;;; let-keywords
;;; let-keywords*
;;; lambda*
;;; define*
-;;; define*-public
+;;; define*-public
;;; defmacro*
;;; defmacro*-public
;;;
;;; are used to indicate grouping only):
;;;
;;; ext-param-list ::= [identifier]* [#:optional [ext-var-decl]+]?
-;;; [#:key [ext-var-decl]+ [#:allow-other-keys]?]?
+;;; [#:key [ext-var-decl]+ [#:allow-other-keys]?]?
;;; [[#:rest identifier]|[. identifier]]?
;;;
-;;; ext-var-decl ::= identifier | ( identifier expression )
+;;; ext-var-decl ::= identifier | ( identifier expression )
;;;
;;; The characters `*', `+' and `?' are not to be taken literally; they
;;; mean respectively, zero or more occurences, one or more occurences,
;;; and one or zero occurences.
;;;
+;;; Code:
-
-;; bound? var
-;; Checks if a variable is bound in the current environment.
-;;
-;; defined? doesn't quite cut it as it stands, since it only
-;; checks bindings in the top-level environment, not those in
-;; local scope only.
-;;
-
-(defmacro-public bound? (var)
- `(catch 'misc-error
- (lambda ()
- ,var
- (not (eq? ,var ,(variable-ref
- (make-undefined-variable)))))
- (lambda args #f)))
-
+(define-module (ice-9 optargs))
;; let-optional rest-arg (binding ...) . body
;; let-optional* rest-arg (binding ...) . body
;; macros used to bind optional arguments
;;
-;; These two macros give you an optional argument interface that
-;; is very "Schemey" and introduces no fancy syntax. They are
-;; compatible with the scsh macros of the same name, but are slightly
+;; These two macros give you an optional argument interface that is
+;; very "Schemey" and introduces no fancy syntax. They are compatible
+;; with the scsh macros of the same name, but are slightly
;; extended. Each of binding may be of one of the forms <var> or
;; (<var> <default-value>). rest-arg should be the rest-argument of
;; the procedures these are used from. The items in rest-arg are
;; sequentially bound to the variable namess are given. When rest-arg
;; runs out, the remaining vars are bound either to the default values
-;; or left unbound if no default value was specified. rest-arg remains
+;; or to `#f' if no default value was specified. rest-arg remains
;; bound to whatever may have been left of rest-arg.
;;
;; duplicates keyword args in the rest arg. More explanation of what
;; keyword arguments in a lambda list look like can be found below in
;; the documentation for lambda*. Bindings can have the same form as
-;; for let-optional. If allow-other-keys? is false, an error will be
+;; for let-optional. If allow-other-keys? is false, an error will be
;; thrown if anything that looks like a keyword argument but does not
;; match a known keyword parameter will result in an error.
;;
;; some utility procedures for implementing the various let-forms.
(define (let-o-k-template REST-ARG BINDINGS BODY let-type proc)
- (let ((bindings (map (lambda (x)
+ (let ((bindings (map (lambda (x)
(if (list? x)
x
- (list x (variable-ref
- (make-undefined-variable)))))
+ (list x #f)))
BINDINGS)))
`(,let-type ,(map proc bindings) ,@BODY)))
(if (null? BINDINGS)
`(begin ,@BODY)
(let-o-k-template REST-ARG BINDINGS BODY let-type
- (lambda (optional)
- `(,(car optional)
+ (lambda (optional)
+ `(,(car optional)
(cond
((not (null? ,REST-ARG))
(let ((result (car ,REST-ARG)))
(bindfilter (lambda (key)
`(,(car key)
(cond
- ((assq ',(car key) ,kb-list-gensym)
+ ((assq ',(car key) ,kb-list-gensym)
=> cdr)
- (else
+ (else
,(cadr key)))))))
- `(let* ((ra->kbl ,rest-arg->keyword-binding-list)
+ `(let* ((ra->kbl ,rest-arg->keyword-binding-list)
(,kb-list-gensym (ra->kbl ,REST-ARG ',(map
(lambda (x) (symbol->keyword (if (pair? x) (car x) x)))
BINDINGS)
(error "Keyword argument has no value.")
(next (cons (cons (keyword->symbol first)
(car rest)) accum))))
- ((not allow-other-keys?)
+ ((not allow-other-keys?)
(error "Unknown keyword in arguments."))
(else (if (null? rest)
accum
;; "#&optional" instead of "#:optional"
(read-hash-extend #\& (lambda (c port)
- (display
- "WARNING: `#&' is deprecated, use `#:' instead\n"
- (current-error-port))
+ (issue-deprecation-warning
+ "`#&' is deprecated, use `#:' instead.")
(case (read port)
((optional) #:optional)
((key) #:key)
;; lambda* args . body
;; lambda extended for optional and keyword arguments
-;;
+;;
;; lambda* creates a procedure that takes optional arguments. These
;; are specified by putting them inside brackets at the end of the
;; paramater list, but before any dotted rest argument. For example,
;; (lambda* (a b #:optional c d . e) '())
;; creates a procedure with fixed arguments a and b, optional arguments c
;; and d, and rest argument e. If the optional arguments are omitted
-;; in a call, the variables for them are unbound in the procedure. This
-;; can be checked with the bound? macro.
+;; in a call, the variables for them are bound to `#f'.
;;
;; lambda* can also take keyword arguments. For example, a procedure
;; defined like this:
;; Optional and keyword arguments can also be given default values
;; which they take on when they are not present in a call, by giving a
;; two-item list in place of an optional argument, for example in:
-;; (lambda* (foo #:optional (bar 42) #:key (baz 73)) (list foo bar baz))
+;; (lambda* (foo #:optional (bar 42) #:key (baz 73)) (list foo bar baz))
;; foo is a fixed argument, bar is an optional argument with default
;; value 42, and baz is a keyword argument with default value 73.
;; Default value expressions are not evaluated unless they are needed
-;; and until the procedure is called.
+;; and until the procedure is called.
;;
;; lambda* now supports two more special parameter list keywords.
;;
(defmacro-public lambda* (ARGLIST . BODY)
- (parse-arglist
+ (parse-arglist
ARGLIST
(lambda (non-optional-args optionals keys aok? rest-arg)
; Check for syntax errors.
(string? (car BODY)))
(list (car BODY))
'())
- (let-optional*
+ (let-optional*
,rest-gensym
,optionals
(let-keywords* ,rest-gensym
`((if (not (null? ,rest-gensym))
(error "Too many arguments.")))
'())
- ,@BODY)))
- `(lambda (,@non-optional-args . ,(if rest-arg rest-arg '()))
+ (let ()
+ ,@BODY))))
+ `(lambda (,@non-optional-args . ,(if rest-arg rest-arg '()))
,@BODY))))))
(every? pred (cdr lst)))))
(define (ext-decl? obj)
- (or (symbol? obj)
+ (or (symbol? obj)
(and (list? obj) (= 2 (length obj)) (symbol? (car obj)))))
(define (parse-arglist arglist cont)
((memq val lst)
=> (lambda (pos)
(if (memq val (cdr pos))
- (error (with-output-to-string
+ (error (with-output-to-string
(lambda ()
- (map display `(,val
+ (map display `(,val
" specified more than once in argument list.")))))
(cont (reverse (cdr (memq val (reverse lst)))) (cdr pos) #t))))
(else (cont lst '() #f))))
(error "#:optional specified but no optional arguments declared.")
(cont before after keys aok? rest)))))
(define (parse-keys arglist rest cont)
- (split-list-at
+ (split-list-at
#:allow-other-keys arglist
(lambda (aok-before aok-after aok-split?)
(if (and aok-split? (not (null? aok-after)))
(error "#:allow-other-keys not at end of keyword argument declarations.")
- (split-list-at
+ (split-list-at
#:key aok-before
(lambda (key-before key-after key-split?)
- (cond
+ (cond
((and aok-split? (not key-split?))
(error "#:allow-other-keys specified but no keyword arguments declared."))
- (key-split?
+ (key-split?
(cond
((null? key-after) (error "#:key specified but no keyword arguments declared."))
((memq #:optional key-after) (error "#:optional arguments declared after #:key arguments."))
(else (parse-opt-and-fixed key-before key-after aok-split? rest cont))))
(else (parse-opt-and-fixed arglist '() #f rest cont)))))))))
(define (parse-rest arglist cont)
- (cond
+ (cond
((null? arglist) (cont '() '() '() #f #f))
((not (pair? arglist)) (cont '() '() '() #f arglist))
((not (list? arglist))
(if (memq #:rest copy)
(error "Cannot specify both #:rest and dotted rest argument.")
(parse-keys copy ra cont))))
- (else (split-list-at
- #:rest arglist
+ (else (split-list-at
+ #:rest arglist
(lambda (before after split?)
(if split?
(case (length after)
;; (define-public* ((foo #:optional bar) #:optional baz) '())
;; This illustrates currying. A procedure foo is defined, which,
;; when called with an optional argument bar, returns a procedure that
-;; takes an optional argument baz.
+;; takes an optional argument baz.
;;
;; Of course, define*[-public] also supports #:rest and #:allow-other-keys
;; in the same way as lambda*.
;; defmacro* name args . body
;; defmacro*-public args . body
;; defmacro and defmacro-public extended for optional and keyword arguments
-;;
+;;
;; These are just like defmacro and defmacro-public except that they
;; take lambda*-style extended paramter lists, where #:optional,
;; #:key, #:allow-other-keys and #:rest are allowed with the usual
`(,DT ,NAME
(,(lambda (transformer) (defmacro:transformer transformer))
(lambda* ,ARGLIST ,@BODY))))
+
+;;; optargs.scm ends here
HCoop / bpt / guile.git / blobdiff