/
case-lambda.scm
45 lines (42 loc) · 1.39 KB
/
case-lambda.scm
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; From official SRFI 16 document at http://srfi.schemers.org/srfi-16/srfi-16.html :
;; This code is in the public domain.
(compile-options no-global-state: #t)
(define-syntax case-lambda
(syntax-rules ()
((case-lambda
(?a1 ?e1 ...)
?clause1 ...)
(lambda args
(let ((l (length args)))
(case-lambda "CLAUSE" args l
(?a1 ?e1 ...)
?clause1 ...))))
((case-lambda "CLAUSE" ?args ?l
((?a1 ...) ?e1 ...)
?clause1 ...)
(if (= ?l (length '(?a1 ...)))
(apply (lambda (?a1 ...) ?e1 ...) ?args)
(case-lambda "CLAUSE" ?args ?l
?clause1 ...)))
((case-lambda "CLAUSE" ?args ?l
((?a1 . ?ar) ?e1 ...)
?clause1 ...)
(case-lambda "IMPROPER" ?args ?l 1 (?a1 . ?ar) (?ar ?e1 ...)
?clause1 ...))
((case-lambda "CLAUSE" ?args ?l
(?a1 ?e1 ...)
?clause1 ...)
(let ((?a1 ?args))
?e1 ...))
((case-lambda "CLAUSE" ?args ?l)
(error "Wrong number of arguments to CASE-LAMBDA."))
((case-lambda "IMPROPER" ?args ?l ?k ?al ((?a1 . ?ar) ?e1 ...)
?clause1 ...)
(case-lambda "IMPROPER" ?args ?l (+ ?k 1) ?al (?ar ?e1 ...)
?clause1 ...))
((case-lambda "IMPROPER" ?args ?l ?k ?al (?ar ?e1 ...)
?clause1 ...)
(if (>= ?l ?k)
(apply (lambda ?al ?e1 ...) ?args)
(case-lambda "CLAUSE" ?args ?l
?clause1 ...)))))