CommonLisp Scheme Part10

191 名前：デフォルトの名無しさん mailto:sage [04/02/21 12:28] >>189 ちょっとあなたのと仕様が違いますが、昔書いたものを。 (defmacro alist-bind ((&rest vars) alist &body body) (let ((tmp (gensym))) `(let ((,tmp ,alist)) (let ,(mapcar #'(lambda (var) `(,var (cdr (assoc ',var ,tmp :test #'eq)))) vars) ,@body)))) (setq data '((a . 1) (b . 2) (c . 3))) (alist-bind (b c a) data (list b c a)) => (2 3 1) (macroexpand-1 '(alist-bind (b c a) data (list b c a))) => (LET ((#:G219 DATA)) (LET ((B (CDR (ASSOC 'B #:G219 :TEST #'EQ))) (C (CDR (ASSOC 'C #:G219 :TEST #'EQ))) (A (CDR (ASSOC 'A #:G219 :TEST #'EQ)))) (LIST B C A)))

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