! :folding=indent:collapseFolds=0:

! $Id$
!
! Copyright (C) 2003, 2004 Slava Pestov.
! 
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IN: logic USE: kernel USE: stack

: ? ( cond t f -- t/f )
    #! Push t if cond is true, otherwise push f.
    rot [ drop ] [ nip ] ifte ; inline

: and ( a b -- a&b )
    #! Logical and.
    f ? ; inline

: not ( a -- a )
    #! Pushes f is the object is not f, t if the object is f.
    f t ? ; inline

: or ( a b -- a|b) 
    #! Logical or.
    t swap ? ; inline

: xor ( a b -- a^b )
    #! Logical exclusive or.
    dup not swap ? ; inline

: >boolean t f ? ; inline

: replace ( obj old new -- obj/new )
    #! If obj is equal to old, drop it and push new.
    >r dupd = [ drop r> ] [ r> drop ] ifte ;