indices ( obj seq -- indices )

Vocabulary

sequences

Inputs

obj	an object
seq	a sequence

Outputs

indices

a sequence

Word description

Compares the input object to every element in the sequence and returns a vector containing the index of every position where the element was found.

Examples

USING: sequences prettyprint ; 2 { 2 4 2 6 2 8 2 10 } indices .
V{ 0 2 4 6 }

Definition

USING: kernel ;

IN: sequences

: indices ( obj seq -- indices )
    swap [ = ] curry [ swap ] prepose V{ } clone
    [ [ push ] curry [ [ drop ] if ] curry compose each-index ]
    keep ;