suzanne.soy/racket
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Superficial pattern for wildcard that doesn't bind.

Browse Source
This commit is contained in:
J. Ian Johnson 2013-06-07 12:15:53 -04:00
parent e25156d67f
commit 214bc7089b
3 changed files with 7 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
collects/redex/private/rewrite-side-conditions.rkt
View File

@ -215,6 +215,7 @@
(define prefix-stx (datum->syntax term prefix-sym))
(define mismatch? (regexp-match? #rx"^!_" suffix))
(cond
[(eq? (syntax-e term) '_) (values `any '())] ;; don't bind wildcard
[(eq? prefix-sym '...)
(raise-syntax-error
what

5
collects/redex/scribblings/ref.scrbl
View File

@ -101,6 +101,7 @@ in the grammar are terminals.
@(racketgrammar* #;#:literals #;(any number string variable variable-except variable-prefix variable-not-otherwise-mentioned hole hide-hole name in-hole side-condition cross)
[pattern any
_
number
natural
integer
@ -134,6 +135,10 @@ were an implicit @pattech[name] @pattern) and match the portion
before the underscore.
}
@item{The @defpattech[_] @pattern matches any sexpression,
but does not bind $pattech[_] as a name, nor can it be suffixed to bind a name.
}
@item{The @defpattech[number] @pattern matches any number.
This @pattern may also be suffixed with an underscore and another
identifier, in which case they bind the full name (as if it

3
collects/redex/tests/rewrite-side-condition-test.rkt
View File

@ -22,6 +22,7 @@
(check-equal? (rsc 1 () #t) `(1 () ()))
(check-equal? (rsc (1) () #t) `((list 1) () ()))
(check-equal? (rsc (_ _ (name x _)) () #t) `((list any any (name x any)) (x) (x)))
(check-equal? (rsc (1 ...) () #t) `((list (repeat 1 #f #f)) () ()))
(check-equal? (rsc (1 ..._2) () #t) `((list (repeat 1 #f #f)) () ()))
(check-equal? (rsc (1 ..._2 1 ..._2) () #t) `((list (repeat 1 ..._2 #f) (repeat 1 ..._2 #f)) () ()))
@ -68,8 +69,6 @@
'(list (repeat (name x_1 (nt x)) ..._2 #f)
(repeat (name x (nt x)) ..._2 #f)
(repeat (name x_1 (nt x)) ..._2 #f)))
(check-equal? (car (rsc (x_1 ..._1 x_2 ..._2 (x_1 x_2) ..._3) (x) #t))
'(list (repeat (name x_1 (nt x)) ..._3 #f)
(repeat (name x_2 (nt x)) ..._3 #f)