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sequences.lib: indices

db4
Eduardo Cavazos 2008-02-03 03:48:58 -06:00
parent 7a5d48cadb
commit 8cfc644893
1 changed files with 10 additions and 0 deletions
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extra/sequences/lib/lib.factor
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@ -140,3 +140,13 @@ PRIVATE>
: ?second ( seq -- second/f ) 1 swap ?nth ; inline : ?second ( seq -- second/f ) 1 swap ?nth ; inline
: ?third ( seq -- third/f ) 2 swap ?nth ; inline : ?third ( seq -- third/f ) 2 swap ?nth ; inline
: ?fourth ( seq -- fourth/f ) 3 swap ?nth ; inline : ?fourth ( seq -- fourth/f ) 3 swap ?nth ; inline
! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! List the positions of obj in seq
: indices ( seq obj -- seq )
>r dup length swap r>
[ = [ ] [ drop f ] if ] curry
2map
[ ] subset ;