Safe Haskell	Safe
Language	Haskell2010

Control.Monad.Free.Reflection

Synopsis

Documentation

data Free f a Source

The abstract Free datatype. Original work available at http://okmij.org/ftp/Haskell/AlgorithmsH1.html#reflection-without-remorse.

Instances

Functor f => Monad (Free f) Source
Functor f => Functor (Free f) Source
Functor f => Applicative (Free f) Source

freePure :: a -> Free f a Source

Inject a pure value into Free

freeImpure :: f (Free f a) -> Free f a Source

Inject an impure value into Free

freeMap Source

Arguments

:: Functor f
=> (a -> t)	function to be applied if value is Pure
-> (f (Free f a) -> t)	function to be applied on Impure value
-> Free f a	Free value to be mapped over
-> t	result

Case analysis for the Free construction. Similar in spirit to either and maybe.

data FreeView f a Source

The traditional view of Free constructions

Constructors

Pure a	case embedding pure values
Impure (f (Free f a))	case embedding impure values nested in `f`. Traditionally this is the `Control.Monad.Free.Free` constructor, but that's confusing.

fromView :: FreeView f a -> Free f a Source

A way to get a Free construction from the view by constructing an explicit expression with one element.

toView :: Functor f => Free f a -> FreeView f a Source

A way to evaluate the Free construction to its view (i.e., head normal form). This includes the logic to perform one level of monadic bind as needed from the FreeExp representation.