3unless ( ..a x y z pred: ( ..a x y z -- ..b ? ) false: ( ..b x y z -- ..c x y z ) -- ..b x y z )


Vocabulary
kernel

Inputs
xan object
yan object
zan object
preda quotation
falsea quotation


Outputs
xan object
yan object
zan object


Word description
A variant of unless that takes a pred quotation. Calls 3check on the pred quotation to return a boolean and preserves x, y, and z for both branches. The false branch is called conditionally.

See also
1if, 1when, 1unless, 2if, 2when, 2unless, 3if, 3when

Definition
IN: kernel

: 3unless
( ..a x y z pred: ( ..a x y z -- ..b ? ) false: ( ..b x y z -- ..c x y z ) -- ..b x y z )
[ ] swap 3if ; inline