managed

A monad for managed values.

In Haskell you very often acquire values using the with... idiom using functions of type (a -> IO r) -> IO r. This idiom forms a Monad, which is a special case of the ContT monad (from transformers) or the Codensity monad (from kan-extensions). The main purpose behind this package is to provide a restricted form of these monads specialized to this unusually common case.

The reason this package defines a specialized version of these types is to:

• be more beginner-friendly,

• simplify inferred types and error messages, and:

• provide some additional type class instances that would otherwise be orphan instances