1unless ( ..a x pred: ( ..a x -- ..b ? ) false: ( ..b x -- ..b x ) -- ..b x )


Vocabulary
kernel

Inputs
xan object
preda quotation
falsea quotation


Outputs
xan object


Word description
A variant of when that takes a pred quotation. Calls 1check on the pred quotation to return a boolean and preserves x for both branches. The false branch is called conditionally.

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

Definition

: 1unless
( ..a x pred: ( ..a x -- ..b ? ) false: ( ..b x -- ..b x ) -- ..b x )
[ ] swap 1if ; inline