Paste: Contuation passing style in Factor

! Copyright (C) 2023 Your name.
! See https://factorcode.org/license.txt for BSD license.
USING: kernel math ;
IN: capital.cps

: dip& ( x y quot quot -- )
    [ dip ] dip call ; inline

: drop& ( x quot -- )
    [ drop ] dip call ; inline 

: *& ( x y quot -- )
    [ * ] dip call ; inline

: -& ( x y  quot -- )
    [ - ] dip call ; inline

: swap& ( x y quot -- )
    [ swap ] dip call ; inline

: over& ( x y quot -- )
    [ over ] dip call ; inline

: +& ( x y quot -- )
    [ + ] dip call ; inline

: nip& ( x y quot -- )
    [ nip ] dip call ; inline

: =& ( x y quot -- )
    [ = ] dip call ; inline

: dup& ( x quot -- )
    [ dup ] dip call ; inline

: times& ( x quot quot -- )
    [ times ] dip call ; inline

! Factor can apparently inline and optimize
! Continuation passing style into the same performance
! as the direct style.
: factorial ( x -- x! )
    dup 0 = [ drop 1 ] 
            [ dup 1 - factorial * ] if ;

: factorial& ( x quot: ( x -- ) -- )
    [ 
        [ 
            0 [ 
                [ [ 1 ] drop& ] 
                [ [ 1 [ [ [ ] *& ] factorial& ] -& ] dup& ] if 
            ] =& 
        ] dup& 
    ] dip call ; inline recursive
 
: fib ( x -- x )
    [ 1 0 ] dip [ over + swap ] times nip ;

: fib& ( x quot -- )
    [ 
        [ 1 0 ] 
        [ 
            [ [ [ [ ] swap& ] &+ ] over& ] 
                              [ [ ] nip& ] times& 
        ] dip& 
    ] dip call ; inline