> On Jun 3, 2019, at 8:51 AM, Matthias Felleisen <matth...@felleisen.org> wrote:
>
>
> My code run your examples. Whay is missinng?
>
Here’s what I’ve been trying to run.
#lang racket
(require (for-syntax racket/syntax)
racket/stxparam)
(define-syntax-parameter false
(lambda (stx)
(raise-syntax-error (syntax-e stx) "can only be used inside lambda.")))
(define-syntax (fn stx)
(syntax-case stx ()
[(_ (arg ...) body0 body ...)
(with-syntax ([return (format-id #'body0 "~a" #'return)])
#'(λ (arg ...) (let/cc return
(syntax-parameterize ([false #'return]) body0 body
...))))]))
((fn (x y) (when (< x y) (return x)) y) 2 30) ; => 2
((fn (x y) (when (< x y) (false)) y) 2 30)
Kevin
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