undo-if* ( result a b -- boolean )

Vocabulary

inverse

Inputs

result	an object
a	an object
b	an object

Outputs

boolean

an object

Definition

USING: combinators kernel ;

IN: inverse

:: undo-if* ( result a b -- boolean )
    b ( -- b ) call-effect result =
    [ f ] [ result a [undo] ( a -- b ) call-effect ] if ;