ExceptT is:exact

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.
A monad transformer that adds exceptions to other monads. ExceptT constructs a strict monad parameterized over two things:
  • e - An arbitrary exception type.
  • m - The inner monad.
The monadic computations are a plain values. They are unrelated to the Control.Exception mechanism, which is tied to the IO monad. The return function yields a computation that produces the given value, while >>= sequences two subcomputations, exiting on the first exception.
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.
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.
A newtype wrapper around ExceptT from transformers that provides less restrictive Applicative, Selective and Alternative instances.