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doc: notes about permutations

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1. limited to lists with <=256 elements
2. add index, so searches for 'rearrangements' go to 'permutations'
This commit is contained in:
Ben Greenman 2018-01-23 13:14:23 -05:00
parent c00340c5f0
commit c7739a14fd
1 changed files with 5 additions and 3 deletions
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pkgs/racket-doc/scribblings/reference/pairs.scrbl
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@ -1352,9 +1352,10 @@ Builds combinations one-by-one instead of all at once.
@defproc[(permutations [lst list?])
list?]{
Returns a list of all permutations of the input list. Note that this
@index["rearrangements"]{Returns} a list of all permutations of the input list. Note that this
function works without inspecting the elements, and therefore it ignores
repeated elements (which will result in repeated permutations).
Raises an error if the input list contains more than 256 elements.
@mz-examples[#:eval list-eval
(permutations '(1 2 3))
@ -1364,9 +1365,10 @@ repeated elements (which will result in repeated permutations).
@defproc[(in-permutations [lst list?])
sequence?]{
Returns a sequence of all permutations of the input list. It is
@index["in-rearrangements"]{Returns} a sequence of all permutations of the input list. It is
equivalent to @racket[(in-list (permutations l))] but much faster since
it builds the permutations one-by-one on each iteration}
it builds the permutations one-by-one on each iteration
Raises an error if the input list contains more than 256 elements.}
@defproc[(argmin [proc (-> any/c real?)] [lst (and/c pair? list?)])