select-by ( ... seq quot: ( ... elt -- ... x ) compare: ( obj1 obj2 -- ? ) -- ... elt )

Vocabulary

sequences.private

Inputs

seq	an object
quot	a quotation with stack effect ( ... elt -- ... x )
compare	a quotation with stack effect ( obj1 obj2 -- ? )

Outputs

elt

an object

Definition

USING: kernel sequences ;

IN: sequences.private

: select-by
    ( ... seq quot: ( ... elt -- ... x ) compare: ( obj1 obj2 -- ? ) -- ... elt )
    [
        [ keep swap ] curry [ [ first ] dip call ] 2keep
        [ curry 2dip pick over ] curry
    ] [ [ [ 2drop ] [ 2nipd ] if ] compose ] bi* compose
    1 each-from drop ; inline