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math.combinatorics: specialized version of nths-unsafe for performance.

db4
John Benediktsson 2013-06-14 11:27:45 -07:00
parent 8262e97309
commit 6c6664b0b8
1 changed files with 13 additions and 3 deletions
basis/math/combinatorics

16
basis/math/combinatorics/combinatorics.factor
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@ -2,13 +2,24 @@
! See http://factorcode.org/license.txt for BSD license.
USING: accessors arrays assocs binary-search classes.tuple
combinators fry hints kernel locals math math.order math.ranges
memoize namespaces sequences sequences.private sorting ;
combinators fry hints kernel kernel.private locals math
math.order math.ranges memoize namespaces sequences
sequences.private sorting strings ;
FROM: sequences => change-nth ;
IN: math.combinatorics
<PRIVATE
! Specialized version of nths-unsafe for performance
: (nths-unsafe) ( indices seq -- seq' )
[ { array } declare ] dip
[ [ nth-unsafe ] curry ] keep map-as ; inline
GENERIC: nths-unsafe ( indices seq -- seq' )
M: string nths-unsafe (nths-unsafe) ;
M: array nths-unsafe (nths-unsafe) ;
M: iota-tuple nths-unsafe (nths-unsafe) ;
M: object nths-unsafe (nths-unsafe) ;
: possible? ( n m -- ? )
0 rot between? ; inline
@ -245,4 +256,3 @@ PRIVATE>
: selections ( seq n -- selections )
dup 0 > [ (selections) ] [ 2drop { } ] if ;