fail package:valor

fail :: Monad m => e -> Valor i m e
valor Data.Valor
Constructs a validator that always fails with provided error e.

Example

>>> validateP ( fail "YOU SHALL NOT PASS!!!" ) 1
Right "YOU SHALL NOT PASS!!!"
failIf :: (Monad m, Monoid e) => e -> (i -> Bool) -> Valor i m e
valor Data.Valor
A validator that fails with e if the predicate returns True.

Example

>>> validateP ( failIf "must be less than or equal to 0" (>0) ) 1
Right "must be less than or equal to 0"

>>> validateP ( failIf "must be less than or equal to 0" (>0) ) (-20)
Left (Valid (-20))
failIfM :: (Monad m, Monoid e) => e -> (i -> m Bool) -> Valor i m e
valor Data.Valor
A monadic version of failIf.