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-rw-r--r--fluidlet.scm43
1 files changed, 19 insertions, 24 deletions
diff --git a/fluidlet.scm b/fluidlet.scm
index c93b288..59ba481 100644
--- a/fluidlet.scm
+++ b/fluidlet.scm
@@ -1,5 +1,5 @@
; "fluidlet.scm", FLUID-LET for Scheme
-; Copyright (c) 1992, Dorai Sitaram (dorai@cs.rice.edu)
+; Copyright (c) 1998, Aubrey Jaffer
;
;Permission to copy this software, to redistribute it, and to use it
;for any purpose is granted, subject to the following restrictions and
@@ -17,29 +17,24 @@
;promotional, or sales literature without prior written consent in
;each case.
-(require 'rev4-optional-procedures)
-(require 'common-list-functions)
(require 'dynamic-wind)
-(require 'macro)
+(require 'common-list-functions) ;MAKE-LIST
-(define list-set! (lambda (s i v) (set-car! (list-tail s i) v)))
-
-(define-syntax fluid-let
- (syntax-rules ()
- ((fluid-let ((x v) ...) . body)
- (let ((%x-names (list 'x ...))
- (%x-values (list x ...))
- (%fluid-x-values (list v ...)))
+(defmacro fluid-let (clauses . body)
+ (let ((ids (map car clauses))
+ (new-tmps (map (lambda (x) (gentemp)) clauses))
+ (old-tmps (map (lambda (x) (gentemp)) clauses)))
+ `(let (,@(map list new-tmps (map cadr clauses))
+ ,@(map list old-tmps (make-list (length clauses) #f)))
(dynamic-wind
- (lambda ()
- (set! x (list-ref %fluid-x-values
- (comlist:position 'x %x-names)))
- ...)
- (lambda () . body)
- (lambda ()
- (let ((%x-position (comlist:position 'x %x-names)))
- (list-set! %fluid-x-values %x-position x)
- (set! x (list-ref %x-values %x-position)))
- ...))))))
-
-;--- end of file
+ (lambda ()
+ ,@(map (lambda (ot id) `(set! ,ot ,id))
+ old-tmps ids)
+ ,@(map (lambda (id nt) `(set! ,id ,nt))
+ ids new-tmps))
+ (lambda () ,@body)
+ (lambda ()
+ ,@(map (lambda (nt id) `(set! ,nt ,id))
+ new-tmps ids)
+ ,@(map (lambda (id ot) `(set! ,id ,ot))
+ ids old-tmps))))))