Cont package:mtl-prelude

Continuation monad. Cont r a is a CPS ("continuation-passing style") computation that produces an intermediate result of type a within a CPS computation whose final result type is r. The return function simply creates a continuation which passes the value on. The >>= operator adds the bound function into the continuation chain.

Construct a continuation-passing computation from a function. (The inverse of runCont)

The continuation monad transformer. Can be used to add continuation handling to any type constructor: the Monad instance and most of the operations do not require m to be a monad. ContT is not a functor on the category of monads, and many operations cannot be lifted through it.

The result of running a CPS computation with the identity as the final continuation.

• evalCont (return x) = x

The result of running a CPS computation with return as the final continuation.

• evalContT (lift m) = m

Apply a function to transform the result of a continuation-passing computation.

• runCont (mapCont f m) = f . runCont
  m

The result of running a CPS computation with a given final continuation. (The inverse of cont)

Apply a function to transform the continuation passed to a CPS computation.

• runCont (withCont f m) = runCont m .
  f