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

Add #:when to more places in match docs

Browse Source 
Also adjusted some examples a bit
This commit is contained in:
Asumu Takikawa 2013-10-31 13:53:28 -04:00
parent 23a0823dec
commit acc4e92a71
1 changed files with 14 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
pkgs/racket-pkgs/racket-doc/scribblings/reference/match.scrbl
View File

@ -378,7 +378,8 @@ appear in the original program.
@defform/subs[(match* (val-expr ...+) clause* ...) @defform/subs[(match* (val-expr ...+) clause* ...)
([clause* [(pat ...+) body ...+] ([clause* [(pat ...+) body ...+]
[(pat ...+) (=> id) body ...+]])]{ [(pat ...+) (=> id) body ...+]
[(pat ...+) #:when cond-expr body ...+]])]{
Matches a sequence of values against each clause in order, matching Matches a sequence of values against each clause in order, matching
only when all patterns in a clause match. Each clause must have the only when all patterns in a clause match. Each clause must have the
same number of patterns as the number of @racket[val-expr]s. same number of patterns as the number of @racket[val-expr]s.
@ -386,6 +387,10 @@ same number of patterns as the number of @racket[val-expr]s.
@examples[#:eval match-eval @examples[#:eval match-eval
(match* (1 2 3) (match* (1 2 3)
[(_ (? number?) x) (add1 x)]) [(_ (? number?) x) (add1 x)])
(match* (15 17)
[((? number? a) (? number? b))
#:when (= (+ a 2) b)
'diff-by-two])
] ]
} }
@ -407,7 +412,8 @@ many values to expect from @racket[expr].
(code:line keyword arg-id) (code:line keyword arg-id)
(code:line keyword [arg-id default-expr])] (code:line keyword [arg-id default-expr])]
[match*-clause [(pat ...+) body ...+] [match*-clause [(pat ...+) body ...+]
[(pat ...+) (=> id) body ...+]]) [(pat ...+) (=> id) body ...+]
[(pat ...+) #:when cond-expr body ...+]])
]{ ]{
Binds @racket[id] to a procedure that is defined by pattern matching Binds @racket[id] to a procedure that is defined by pattern matching
clauses using @racket[match*]. Each clause takes a sequence of clauses using @racket[match*]. Each clause takes a sequence of
@ -415,15 +421,17 @@ many values to expect from @racket[expr].
The arguments are ordered as they appear in the function header for The arguments are ordered as they appear in the function header for
matching purposes. matching purposes.
The function header may contain optional or keyword arguments, or
may be in curried form.
@defexamples[#:eval match-eval @defexamples[#:eval match-eval
(define/match (fact n) (define/match (fact n)
[(0) 1] [(0) 1]
[(n) (* n (fact (sub1 n)))]) [(n) (* n (fact (sub1 n)))])
(fact 5) (fact 5)
]
The function header may also contain optional or keyword arguments,
may have curried arguments, and may also contain a rest argument.
@defexamples[#:eval match-eval
(define/match ((f x) #:y [y '(1 2 3)]) (define/match ((f x) #:y [y '(1 2 3)])
[((regexp #rx"p+") `(,a 2 3)) a] [((regexp #rx"p+") `(,a 2 3)) a]
[(_ _) #f]) [(_ _) #f])