ppush ( val seq -- seq' )
Persistent sequence protocol

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Vocabulary
persistent.sequences

Inputs

val	an object
seq	a sequence

Outputs

seq'	a sequence

Generic word contract
Persistent analogue of push. Outputs a new sequence with all elements of seq together with val added at the end.

Definition

IN: persistent.sequences

GENERIC: ppush ( val seq -- seq' )

Methods

USING: accessors kernel math persistent.sequences
persistent.vectors persistent.vectors.private ;

M: persistent-vector ppush
    clone dup tail>> full? [ ppush-new-tail ] [ ppush-tail ] if
    [ 1 + ] change-count ;


USING: kernel persistent.sequences sequences ;

M: sequence ppush swap suffix ;


USING: kernel math persistent.sequences sequences vlists
vlists.private ;

M: vlist ppush
    >vlist< 2dup length = [ unshare ] unless
    [ [ 1 + swap ] dip push ] keep vlist boa ;