MonadError
public protocol MonadError : ApplicativeError, Monad
A MonadError has the same capabilities as a Monad
and an ApplicativeError
.
-
ensure(_:_:_:)
Extension methodChecks if the value of a computation matches a predicate, raising an error if not.
Declaration
Parameters
fa
A computation in the context implementing this instance.
error
A function that produces an error of the type this instance is able to handle.
predicate
A boolean predicate to test the value of the computation.
Return Value
A value or an error in the context implementing this instance.