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Support for rest arguments to functions with (f . rest), useful for (?@ . blah)

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Georges Dupéron 2017-02-03 09:24:28 +01:00
parent a0df96cb3a
commit 74f38a3213
1 changed files with 6 additions and 5 deletions
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11
ddd-forms.rkt
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@ -105,18 +105,19 @@
;#:with expanded #'(#%app list other)
#:with expanded #'other))
(define-syntax-class not-stx-pair
(pattern {~not (_ . _)})))
(pattern () #:with v #''())
(pattern {~and v {~not (_ . _)}})))
(define-syntax app
(syntax-parser
[{~and (_ fn arg:arg … #;.rest:not-stx-pair)
[{~and (_ fn arg:arg … . rest:not-stx-pair)
{~not (_ _ {~literal …} . _)}} ;; not fn directly followed by a …
;#'(#%app apply fn (#%app append arg.expanded …))
(syntax/top-loc this-syntax
(#%app apply fn (#%app splice-append arg.expanded … #;#:rest #;rest)))]
[(_ arg:arg … #;.rest:not-stx-pair) ;; shorthand for list creation
(#%app apply fn (#%app splice-append arg.expanded … #:rest rest.v)))]
[(_ arg:arg … . rest:not-stx-pair) ;; shorthand for list creation
;#'(#%app apply list (#%app append arg.expanded …))
(syntax/top-loc this-syntax
(#%app apply list (#%app splice-append arg.expanded … #;#:rest #;rest)))]))
(#%app apply list (#%app splice-append arg.expanded … #:rest rest.v)))]))
(define (splice-append #:rest [rest '()] . l*)
(splice-append* (if (null? rest) l* (append l* rest))))