even-indices ( seq -- seq' )

Vocabulary

sequences.extras

Inputs

seq	a sequence

Outputs

seq'	a sequence

Word description

Push a sequence containing the even-indexed elements in seq.

Definition

USING: kernel math sequences sequences.private ;

IN: sequences.extras

: even-indices ( seq -- seq' )
    [ length 1 + 2/ ] keep
    [ [ [ 2 * ] dip nth-unsafe ] curry ] keep map-integers-as ;