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

Allow variables in unquote-splicing terms

Browse Source 
I think that in general, `null-terminated?` should admit all patterns
that _could_ match a list, instead of just the ones that _only_ match
a list. That means that `(app f)` patterns and many others should also
be valid, though those are harder to implement, so I haven't tried
those yet.
This commit is contained in:
Pavel Panchekha 2021-01-02 16:00:01 -07:00 committed by shhyou
parent 4c6bb055b0
commit b56276c670
2 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
pkgs/racket-test/tests/match/examples.rkt
View File

@ -785,6 +785,11 @@
[`(begin ,es ... ,en) [`(begin ,es ... ,en)
(list es en)])) (list es en)]))
(comp '((1 2 3 4) (6 7) (9))
(match '(0 1 2 3 4 5 6 7 8 9)
[`(0 ,@a 5 ,@b 8 ,@c)
(list a b c)]))
(comp '(a b c) (comp '(a b c)
(let () (let ()

7
racket/collects/racket/match/parse-quasi.rkt
View File

@ -11,6 +11,7 @@
(cond [(Pair? pat) (null-terminated? (Pair-d pat))] (cond [(Pair? pat) (null-terminated? (Pair-d pat))]
[(GSeq? pat) (null-terminated? (GSeq-tail pat))] [(GSeq? pat) (null-terminated? (GSeq-tail pat))]
[(Null? pat) #t] [(Null? pat) #t]
[(Var? pat) #t]
[else #f])) [else #f]))
;; combine a null-terminated pattern with another pattern to match afterwards ;; combine a null-terminated pattern with another pattern to match afterwards
@ -23,6 +24,12 @@
(append-pats (GSeq-tail p1) p2) (append-pats (GSeq-tail p1) p2)
(GSeq-mutable? p1))] (GSeq-mutable? p1))]
[(Null? p1) p2] [(Null? p1) p2]
[(Var? p1) (make-GSeq (list (list p1))
(list #f)
(list #f)
(list #f)
p2
#f)]
[else (error 'match "illegal input to append-pats")])) [else (error 'match "illegal input to append-pats")]))
(define hard-case? (define hard-case?