Below two versions of a very stripped version of a macro I have made.
In version 1 background expansion and check-syntax show binding arrows
within macro stx-case.
However, in version 2 the arrows are not shown.
How come?
Thanks, Jos
#lang racket
(require (for-syntax racket))
;;; version 1
(begin-for-syntax
(define-syntax (stx-case stx) ; Here background expansion and macro stepper
(syntax-case stx () ; do show binding arrows in stx-case.
((_ stx-expr clause ...)
(with-syntax
((+ (datum->syntax stx '+))
(- (datum->syntax stx '-))
(* (datum->syntax stx '*))
(/ (datum->syntax stx '/)))
#'(syntax-case stx-expr (+ - * /) clause ...))))))
(define-syntax (a stx)
(stx-case stx
((_ +) #''plus)
((_ -) #''minus)
((_ *) #''mult)
((_ /) #''div)
((_ x) #''x)))
;;; version 2
(define-syntax (b stx)
(define-syntax (stx-case stx) ; Here background expansion and macro stepper
(syntax-case stx () ; do NOT show binding arrows in stx-case.
((_ stx-expr clause ...)
(with-syntax
((+ (datum->syntax stx '+))
(- (datum->syntax stx '-))
(* (datum->syntax stx '*))
(/ (datum->syntax stx '/)))
#'(syntax-case stx-expr (+ - * /) clause ...)))))
(stx-case stx
((_ +) #''plus)
((_ -) #''minus)
((_ *) #''mult)
((_ /) #''div)
((_ x) #''x)))
; Both a and b work correctly:
(a +)
(a else)
(b -)
(b else)
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