ExceptT package:automaton

A monad transformer that adds exceptions to other monads. ExceptT constructs a monad parameterized over two things:

• e - The exception type.
• m - The inner monad.

The return function yields a computation that produces the given value, while >>= sequences two subcomputations, exiting on the first exception.

Convert exceptions into Nothing, discarding the exception value.

Convert a ExceptT computation to MaybeT, discarding the value of any exception.

Embed an ExceptT value inside the Automaton. Whenever the input value is an ordinary value, it is passed on. If it is an exception, it is raised.

The inverse of ExceptT.

Convert a MaybeT computation to ExceptT, with a default exception value.