IOSpec-0.2.1: A pure specification of the IO monad. Source code Contents Index

Test.IOSpec.Types

Contents The IOSpec type. Coproducts of functors Injections from one functor to another

Description

This module contains the basic data types underlying the IOSpec library. Most of the types and classes in this module are described in http://www.cs.nott.ac.uk/~wss/Publications/DataTypesALaCarte.pdf.

Synopsis

data IOSpec f a = Pure a | Impure (f (IOSpec f a)) foldIOSpec :: Functor f => (a -> b) -> (f b -> b) -> IOSpec f a -> b data (f :+: g) x = Inl (f x) | Inr (g x) class (Functor sub, Functor sup) => sub :<: sup inject :: g :<: f => g (IOSpec f a) -> IOSpec f a

The IOSpec type.

data IOSpec f a Source

A value of type IOSpec f a is either a pure value of type a or some effect, determined by f. Crucially, IOSpec f is a monad, provided f is a functor. Constructors Pure a Impure (f (IOSpec f a)) Instances Functor f => Monad (IOSpec f) Functor f => Functor (IOSpec f)

foldIOSpec :: Functor f => (a -> b) -> (f b -> b) -> IOSpec f a -> b Source

The fold over IOSpec values.

Coproducts of functors

data (f :+: g) x Source

The coproduct of functors Constructors Inl (f x) Inr (g x) Instances (f :<: g, Functor f, Functor g, Functor h) => f :<: (h :+: g) (Functor f, Functor g) => f :<: (f :+: g) (Functor f, Functor g) => Functor (f :+: g) (Executable f, Executable g) => Executable (f :+: g)

Injections from one functor to another

class (Functor sub, Functor sup) => sub :<: sup Source

The (:<:) class Instances (f :<: g, Functor f, Functor g, Functor h) => f :<: (h :+: g) (Functor f, Functor g) => f :<: (f :+: g)

inject :: g :<: f => g (IOSpec f a) -> IOSpec f a Source

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