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Documented normalized-arity?, arity=?, and arity-includes?.

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Carl Eastlund 2013-03-30 21:05:02 -04:00
parent 636f8a91dc
commit aaa99d565d
1 changed files with 76 additions and 11 deletions
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87
collects/scribblings/reference/procedures.scrbl
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@ -127,10 +127,11 @@ the @exnraise[exn:fail:contract].
]}
@defproc[(procedure-arity [proc procedure?])
procedure-arity?]{
(and/c procedure-arity? normalized-arity?)]{
Returns information about the number of by-position arguments accepted
by @racket[proc]. See also @racket[procedure-arity?].}
by @racket[proc]. See also @racket[procedure-arity?] and
@racket[normalized-arity?].}
@defproc[(procedure-arity? [v any/c]) boolean?]{
@ -152,7 +153,7 @@ A valid arity @racket[_a] is one of the following:
]
The result of @racket[procedure-arity] is always normalized in the sense of
@racket[normalize-arity].
@racket[normalized-arity?].
@mz-examples[
(procedure-arity cons)
@ -611,10 +612,9 @@ arguments, and following steps add arguments to the left of these.
(map (curryr list 'foo) '(1 2 3))
]}
@defproc[(normalize-arity [arity procedure-arity?]) procedure-arity?]{
@defproc[(normalized-arity? [arity procedure-arity?]) boolean?]{
Produces a normalized form of @racket[arity]. Specifically, the result has one
of the following forms:
A normalized arity has one of the following forms:
@itemize[
@item{the empty list;}
@item{an exact non-negative integer;}
@ -625,12 +625,27 @@ or}
followed by a single @racket[arity-at-least] instance whose value is greater
than the preceding integer by at least 2.}
]
Based on these restrictions, for any two procedure arity values @racket[a] and
@racket[b], @racket[(equal? (normalize-arity a) (normalize-arity b))] produces
a true value if and only if @racket[a] and @racket[b] represent the same set of
numbers of arguments.
Any two normalized arity values that are @racket[arity=?] must also be
@racket[equal?].
@mz-examples[
@mz-examples[#:eval fun-eval
(normalized-arity? (arity-at-least 1))
(normalized-arity? (list (arity-at-least 1)))
(normalized-arity? (list 0 (arity-at-least 2)))
(normalized-arity? (list (arity-at-least 2) 0))
(normalized-arity? (list 0 2 (arity-at-least 3)))
]
}
@defproc[(normalize-arity [arity procedure-arity?])
(and/c procedure-arity? normalized-arity?
(lambda (x) (arity=? x arity)))]{
Produces a normalized form of @racket[arity]. See also
@racket[normalized-arity?] and @racket[arity=?].
@mz-examples[#:eval fun-eval
(normalize-arity 1)
(normalize-arity (list 1))
(normalize-arity (arity-at-least 2))
@ -644,5 +659,55 @@ numbers of arguments.
}
@defproc[(arity=? [a procedure-arity?] [b procedure-arity?]) boolean?]{
Returns @racket[#true] if procedures with arity @racket[a] and @racket[b]
accept the same numbers of arguments, and @racket[#false] otherwise.
Equivalent to both @racket[(and (arity-includes? a b) (arity-includes? b a))]
and @racket[(equal? (normalize-arity a) (normalize-arity b))].
@mz-examples[#:eval fun-eval
(arity=? 1 1)
(arity=? (list 1) 1)
(arity=? 1 (list 1))
(arity=? 1 (arity-at-least 1))
(arity=? (arity-at-least 1) 1)
(arity=? 1 (arity-at-least 1))
(arity=? (arity-at-least 1) (list 1 (arity-at-least 2)))
(arity=? (list 1 (arity-at-least 2)) (arity-at-least 1))
(arity=? (arity-at-least 1) (list 1 (arity-at-least 3)))
(arity=? (list 1 (arity-at-least 3)) (arity-at-least 1))
(arity=? (list 0 1 2 (arity-at-least 3)) (list (arity-at-least 0)))
(arity=? (list (arity-at-least 0)) (list 0 1 2 (arity-at-least 3)))
(arity=? (list 0 2 (arity-at-least 3)) (list (arity-at-least 0)))
(arity=? (list (arity-at-least 0)) (list 0 2 (arity-at-least 3)))
]
}
@defproc[(arity-includes? [a procedure-arity?] [b procedure-arity?]) boolean?]{
Returns @racket[#true] if procedures with arity @racket[a] accept any number of
arguments that procedures with arity @racket[b] accept.
@mz-examples[#:eval fun-eval
(arity-includes? 1 1)
(arity-includes? (list 1) 1)
(arity-includes? 1 (list 1))
(arity-includes? 1 (arity-at-least 1))
(arity-includes? (arity-at-least 1) 1)
(arity-includes? 1 (arity-at-least 1))
(arity-includes? (arity-at-least 1) (list 1 (arity-at-least 2)))
(arity-includes? (list 1 (arity-at-least 2)) (arity-at-least 1))
(arity-includes? (arity-at-least 1) (list 1 (arity-at-least 3)))
(arity-includes? (list 1 (arity-at-least 3)) (arity-at-least 1))
(arity-includes? (list 0 1 2 (arity-at-least 3)) (list (arity-at-least 0)))
(arity-includes? (list (arity-at-least 0)) (list 0 1 2 (arity-at-least 3)))
(arity-includes? (list 0 2 (arity-at-least 3)) (list (arity-at-least 0)))
(arity-includes? (list (arity-at-least 0)) (list 0 2 (arity-at-least 3)))
]
}
@close-eval[fun-eval]