> On Dec 9, 2018, at 8:20 PM, default.kra...@gmail.com wrote:
> Is there an easy way to disallow certain characters in identifiers? I
> realized it's not just dots I want to disallow, but also operators like +
> which might be interpreted as infix in certain contexts.
Roughly, I imagine you'd want to
1) grab the input to `#%module-begin`, which is a tree-shaped syntax object
2) flatten it
3) search the list for forbidden identifiers (using `identifier?` and whatever
patterns are forbidden)
4) report errors, or
5) if none, complete `#%module-begin` as usual.
Like so:
;; "kapu.rkt"
#lang racket
(require (for-syntax racket/list))
(provide (except-out (all-from-out racket) #%module-begin)
(rename-out [mb #%module-begin]))
(define-syntax (mb stx)
(syntax-case stx ()
[(_ . EXPRS)
(let ()
(for ([id (in-list (filter identifier?
(flatten
(let loop ([stx #'EXPRS])
(define maybe-stxs (syntax->list stx))
(if maybe-stxs (map loop maybe-stxs)
stx)))))]
#:when (regexp-match #rx"\\.|\\+" (format "~a" (syntax->datum
id))))
(raise-syntax-error 'mylang "invalid identifier name"
(syntax->datum id)))
#'(#%module-begin . EXPRS))]))
;; "test.rkt"
#lang s-exp "kapu.rkt"
(define foobar 42)
(define foo.bar 42)
(define foo+bar 42)
> mylang: invalid identifier name in: foo.bar
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