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

Added documentation for normalize-arity.

Browse Source
This commit is contained in:
Carl Eastlund 2013-03-30 15:49:36 -04:00
parent e356c660ea
commit 4dd011aa09
1 changed files with 35 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
collects/scribblings/reference/procedures.scrbl
View File

@ -151,13 +151,8 @@ A valid arity @racket[_a] is one of the following:
]
Generally, @racket[procedure-arity] always produces an arity that is normalized.
Specifically, it is either the empty list (corresponding to the procedure
@racket[(case-lambda)]), one of the first two cases above, or a list
that contains at least two elements. If it is a list, there is at most one
@racket[arity-at-least] instance that appears as the last element of the list,
all of the other elements are sorted in ascending order, and there are no duplicate
elements.
The result of @racket[procedure-arity] is always normalized in the sense of
@racket[normalize-arity].
@mz-examples[
(procedure-arity cons)
@ -616,5 +611,38 @@ 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?]{
Produces a normalized form of @racket[arity]. Specifically, the result has one
of the following forms:
@itemize[
@item{the empty list;}
@item{an exact non-negative integer;}
@item{an @racket[arity-at-least] instance;}
@item{a list of two or more strictly increasing, exact non-negative integers;
or}
@item{a list of one or more strictly increasing, exact non-negative integers
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.
@mz-examples[
(normalize-arity 1)
(normalize-arity (list 1))
(normalize-arity (arity-at-least 2))
(normalize-arity (list (arity-at-least 2)))
(normalize-arity (list 1 (arity-at-least 2)))
(normalize-arity (list (arity-at-least 2) 1))
(normalize-arity (list (arity-at-least 2) 3))
(normalize-arity (list 3 (arity-at-least 2)))
(normalize-arity (list (arity-at-least 6) 0 2 (arity-at-least 4)))
]
}
@close-eval[fun-eval]