MonadError

public protocol MonadError : ApplicativeError, Monad

A MonadError has the same capabilities as a Monad and an ApplicativeError.


                    
                    
                    
                      ensure(_:_:_:)

Extension method

Checks if the value of a computation matches a predicate, raising an error if not.

Swift

static func ensure<A>(
    _ fa: Kind<Self, A>,
    _ error: @escaping () -> E,
    _ predicate: @escaping (A) -> Bool) -> Kind<Self, A>

`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.

A value or an error in the context implementing this instance.


                    
                    
                    
                      flatTapError(_:_:)

Extension method

Applies a monadic function to an effect discarding the output.

Swift

static func flatTapError<A, B>(
    _ fa: Kind<Self, A>,
    _ f: @escaping (E) -> Kind<Self, B>) -> Kind<Self, A>

`fa`	A computation.
`f`	A monadic function which result will be discarded.

A computation with the effect of the initial computation.