Here's a much shorter version that doesn't require goto emulation, and
is also almost syntax-rules-kosher, modulo a syntax parameter for
breaking:
-------------------------------------------------------------------------------
#lang racket
(provide cas-cad-e)
(require racket/stxparam)
(define-syntax-parameter break
(lambda (stx)
(raise-syntax-error #f "break must be used inside a cas-cad-e")))
(define-syntax helper
(syntax-rules ()
[(_ v*s tail val [(v0 ...) e0 ...] [v e ...] ...)
(helper (v0 ... . v*s) (when (memq val '(v0 ... . v*s)) tail e0 ...)
val [v e ...] ...)]
[(_ _ tail val) tail]))
(define-syntax-rule (cas-cad-e expr [v e ...] ...)
(let ([val expr])
(let/ec escape
(syntax-parameterize ([break (make-rename-transformer #'escape)])
(helper () (void) val [v e ...] ...)))))
-------------------------------------------------------------------------------
--
((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay:
http://barzilay.org/ Maze is Life!
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