! Copyright (C) 2009 Yun, Jonghyouk.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel locals math sequences sequences.last ;
IN: math.fibonacci

: fib-next ( seq -- n ) [ last-0 ] [ last-1 ] bi + ;

: fib-next-push ( seq -- newseq ) dup fib-next suffix ;

: fib-initial-seq ( -- seq ) { 1 1 } ;

: fib-produce-seq ( seq max -- newseq )
    [let | max_ [ ]
           seq_ [ ] |
        seq_ fib-next max_ <
        [ seq_ fib-next-push max_ fib-produce-seq ]
        [ seq_ ]
        if ] ;