?head ( seq begin -- newseq ? )
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?head-slice ( seq begin -- newseq ? )

Vocabulary
splitting

Inputs

seq	a sequence
begin	a sequence

Outputs

newseq	a new sequence
?	a boolean

Word description
Tests if seq starts with begin. If there is a match, outputs the subrange of seq excluding begin, and t. If there is no match, outputs seq and f.

Definition

USING: sequences splitting.private ;

IN: splitting

: ?head ( seq begin -- newseq ? ) [ head? ] [ tail ] ?chomp ;