Safe Haskell	None
Language	Haskell2010
Extensions	BangPatterns FlexibleContexts KindSignatures RankNTypes ExplicitForAll

Control.THEff.Reader.Strict

Contents

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

Synopsis

Overview

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

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

import Control.THEff
import Control.THEff.Reader.Strict

mkEff "CharReader"   ''Reader    ''Char       ''NoEff
mkEff "StrReader"    ''Reader    ''String     ''CharReader

main:: IO ()
main = putStrLn $ runCharReader 'T' $ runStrReader "est" $ do
            c <- ask
            s <- ask
            return $ c:s

Output : Test

Types and functions used in mkEff

data Reader' v e Source

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

data Reader 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

ReaderOuter (o m e)
ReaderAction (Reader' v e)
ReaderResult a

type ReaderArgT v = v Source

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

type ReaderResT r = r Source

Result type of runEEEE.

effReader :: EffClass Reader' v e => Reader' 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.

runEffReader Source

Arguments

:: forall (t :: * -> ) (u :: ( -> ) -> -> ) (m :: -> ) (m1 :: -> ) (o :: ( -> ) -> -> *). Monad m
=> (u t r -> (r -> m (ReaderResT a)) -> m (ReaderResT a))	The outer effect function
-> (Reader m1 e o w a1 -> r)	The chain of effects link wrapper.
-> (r -> Reader t r u v a)	The chain of effects link unwrapper.
-> ReaderArgT v	The initial value of argument of effect.
-> Eff r a1
-> m (ReaderResT a)

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

Functions that use this effect

ask :: EffClass Reader' v e => Eff e v Source

Get reader value

asks :: EffClass Reader' r e => (r -> v) -> Eff e v Source

Get and convert the value of the reader