rotate! ( seq n -- )

Vocabulary

sequences.extras

Inputs

seq	a sequence
n	an integer

Outputs

None

Word description

A version of rotate that modifies seq in place.

Definition

USING: kernel math sequences sequences.private ;

IN: sequences.extras

:: rotate! ( seq n -- )
    seq length :> len n len mod dup 0 < [ len + ] when
    seq bounds-check drop 0 over
    [ 2dup = ] [
        [ seq exchange-unsafe ] [ [ 1 + ] bi@ ] 2bi dup len =
        [ drop over ] when 2over = [ -rot nip over ] when
    ] until 3drop ;