[plt-dev] Symptom of REPL's hopelessness?

From: Sam TH (samth at ccs.neu.edu)
Date: Thu Oct 1 16:11:08 EDT 2009

On Thu, Oct 1, 2009 at 4:01 PM, Casey Klein
<clklein at eecs.northwestern.edu> wrote:
> Can someone explain why this macro expands without error in a module
> but not in the REPL?
> (define-syntax (m stx)
>  (syntax-case stx ()
>   [(_ x)
>    (with-syntax ([(y) (generate-temporaries (syntax (x)))])
>      (syntax (define (y) y)))]))
>> (m q)
> compile: unbound identifier (and no #%top syntax transformer is bound) in: q1

This version of the macro works:

(define-syntax (m stx)
 (syntax-case stx ()
  [(_ x)
   (with-syntax ([(y) (list (gensym (syntax-e #'x)))])
     (syntax (define (y) y)))]))

sam th
samth at ccs.neu.edu

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