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authorMarius Vollmer <mvo@zagadka.de>2004-01-21 00:46:10 +0000
committerMarius Vollmer <mvo@zagadka.de>2004-01-21 00:46:10 +0000
commitfeeef4fb40adc27426a4ccf98c4131e9133c97f2 (patch)
treecebcf56dd956c9cf185462d8eda02581af018c7d /srfi/srfi-26.scm
parent012a3a7537d305b5ce2f95f3337978facac8634f (diff)
downloadguile-feeef4fb40adc27426a4ccf98c4131e9133c97f2.tar.gz
New, from Daniel Skarda. Thanks!
Diffstat (limited to 'srfi/srfi-26.scm')
-rw-r--r--srfi/srfi-26.scm31
1 files changed, 31 insertions, 0 deletions
diff --git a/srfi/srfi-26.scm b/srfi/srfi-26.scm
new file mode 100644
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+++ b/srfi/srfi-26.scm
@@ -0,0 +1,31 @@
+(define-module (srfi srfi-26)
+ :export (cut cute))
+
+(cond-expand-provide (current-module) '(srfi-26))
+
+(define-macro (cut slot . slots)
+ (let loop ((slots (cons slot slots))
+ (params '())
+ (args '()))
+ (if (null? slots)
+ `(lambda ,(reverse! params) ,(reverse! args))
+ (let ((s (car slots))
+ (rest (cdr slots)))
+ (case s
+ ((<>)
+ (let ((var (gensym)))
+ (loop rest (cons var params) (cons var args))))
+ ((<...>)
+ (if (pair? rest)
+ (error "<...> not on the end of cut expression"))
+ (let ((var (gensym)))
+ `(lambda ,(append! (reverse! params) var)
+ (apply ,@(reverse! (cons var args))))))
+ (else
+ (loop rest params (cons s args))))))))
+
+(define-macro (cute . slots)
+ (let ((temp (map (lambda (s) (and (not (memq s '(<> <...>))) (gensym)))
+ slots)))
+ `(let ,(delq! #f (map (lambda (t s) (and t (list t s))) temp slots))
+ (cut ,@(map (lambda (t s) (or t s)) temp slots)))))