Safe Haskell	None
Language	Haskell2010
Extensions	BangPatterns FlexibleContexts KindSignatures RankNTypes ExplicitForAll

Control.THEff.State.Strict

Contents

Overview
Types and functions used in mkEff
Functions that use this effect
Helper functions

Synopsis

Overview

This version builds its output strictly; for a lazy version with the same interface, see Control.THEff.State.

{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TemplateHaskell #-}

import Control.THEff
import Control.THEff.State.Strict

mkEff "Example1"   ''State     ''Int      ''NoEff
mkEff "Example2"   ''State     ''Float    ''Example1

main:: IO ()
main = print $ runExample1 123 
             $ runExample2 pi $ do
                    i <- get
                    modify ((1 :: Int) +)
                    put $ i * (2 :: Float)
                    return  $ show i

Output : (("3.1415927",6.2831855),124)

Types and functions used in mkEff

data State' v e Source

Actually, the effect type - v - Type - the parameter of the effect. - e - mkEff generated type.

data State m e o v a Source

Type implements link in the chain of effects. Constructors must be named {EffectName}{Outer|WriterAction|WriterResult} and have a specified types of fields. - m - Or Monad (if use the Lift) or phantom type - stub (if used NoEff). - o - Type of outer effect. - a - The result of mkEff generated runEEEE... function.

Constructors

StateOuter (o m e)
StateAction (State' v e)
StateResult a

type StateArgT v = v Source

Type of fourth argument of runEffState and first argument of runEEEE.

type StateResT r v = (r, v) Source

Result type of runEEEE.

effState :: EffClass State' v e => State' v r -> Eff e r Source

This function is used in the mkEff generated runEEEE functions and typically in effect action functions. Calling the effect action.

runEffState Source

Arguments

:: forall (t :: * -> ) (u :: ( -> ) -> -> ) (m :: -> ) (m1 :: -> ) (o :: ( -> ) -> -> *). Monad m
=> (u t r -> (r -> m (StateResT z v)) -> m (StateResT z v))	The outer effect function
-> (State m1 e o w a -> r)	The chain of effects link wrapper.
-> (r -> State t r u v z)	The chain of effects link unwrapper.
-> StateArgT v	The initial value of argument of effect.
-> Eff r a
-> m (StateResT z v)

The main function of the effect implementing. This function is used in the mkEff generated runEEEE functions.

Functions that use this effect

get :: EffClass State' v e => Eff e v Source

Get state value

put :: EffClass State' v e => v -> Eff e () Source

Put state value

modify :: EffClass State' v e => (v -> v) -> Eff e () Source

Modify state value

Helper functions

stateOnly Source

Arguments

:: (t -> e -> (r, v))	State effect runEEEE function
-> t	The initial value of argument of effect.
-> e	Eff (MyState m ...) ...
-> v

 stateOnly runExample1 123 === snd (runExample1 123)

withoutState Source

Arguments

:: (t -> e -> (r, v))	State effect runEEEE function
-> t	The initial value of argument of effect.
-> e	Eff (MyState m ...) ...
-> r

 withoutState runExample1 123 === fst (runExample1 123)