Copyright	(c) 2020 Microsoft Research; Daan Leijen; Ningning Xie
License	MIT
Maintainer	xnning@hku.hk; daan@microsoft.com
Stability	Experimental
Safe Haskell	None
Language	Haskell2010

Examples

Description

Examples from "Effect Handlers in Haskell, Evidently", Ningning Xie and Daan Leijen, Haskell 2020.

Documentation

data Reader a e ans Source #

Constructors

Reader
Fields ask :: Op () a e ans

hr :: a -> Reader a e ans Source #

reader :: a -> Eff (Reader a :* e) ans -> Eff e ans Source #

sample1 :: Eff e [Char] Source #

greetOrExit :: (Reader String :? e, Reader Bool :? e) => Eff e String Source #

greetMaybe :: Reader String :? e => Eff e (Maybe String) Source #

greet :: Reader String :? e => Eff e String Source #

helloWorld :: Eff e String Source #

data Exn e ans Source #

Constructors

Exn
Fields failure :: forall a. Op () a e ans

toMaybe :: Eff (Exn :* e) a -> Eff e (Maybe a) Source #

exceptDefault :: a -> Eff (Exn :* e) a -> Eff e a Source #

safeDiv :: Exn :? e => Int -> Int -> Eff e Int Source #

safeHead :: Exn :? e => String -> Eff e Char Source #

sample3 :: Eff e (Maybe (Maybe Char)) Source #

data State a e ans Source #

Constructors

State
Fields get :: Op () a e ans put :: Op a () e ans

state :: a -> Eff (State a :* e) ans -> Eff e ans Source #

add :: State Int :? e => Int -> Eff e () Source #

invert :: State Bool :? e => Eff e Bool Source #

test :: Eff e Bool Source #

adder :: Eff e [Char] Source #

data Output e ans Source #

Constructors

Output
Fields out :: Op String () e ans

output :: Eff (Output :* e) ans -> Eff e (ans, String) Source #

data Amb e ans Source #

Constructors

Amb
Fields flip :: Op () Bool e ans

xor :: Amb :? e => Eff e Bool Source #

allResults :: Eff (Amb :* e) a -> Eff e [a] Source #

firstResult :: Eff (Amb :* e) (Maybe a) -> Eff e (Maybe a) Source #

solutions :: Eff (Exn :* (Amb :* e)) a -> Eff e [a] Source #

eager :: Eff (Exn :* (Amb :* e)) a -> Eff e (Maybe a) Source #

choice :: Amb :? e => Eff e a -> Eff e a -> Eff e a Source #

many :: Amb :? e => Eff e a -> Eff e [a] Source #

many1 :: Amb :? e => Eff e a -> Eff e [a] Source #

data Parse e ans Source #

Constructors

Parse
Fields satisfy :: forall a. Op (String -> Maybe (a, String)) a e ans

parse :: Exn :? e => String -> Eff (Parse :* e) b -> Eff e (b, String) Source #

symbol :: Parse :? e => Char -> Eff e Char Source #

digit :: Parse :? e => Eff e Int Source #

expr :: (Parse :? e, Amb :? e) => Eff e Int Source #

term :: (Parse :? e, Amb :? e) => Eff e Int Source #

factor :: (Parse :? e, Amb :? e) => Eff e Int Source #

number :: (Parse :? e, Amb :? e) => Eff e Int Source #

test1 :: [(Int, String)] Source #

test2 :: Maybe (Int, String) Source #

data Evil e ans Source #

Constructors

Evil
Fields evil :: Op () () e ans

hevil :: Eff (Evil :* e) a -> Eff e (() -> Eff e a) Source #

ebody :: (Reader Int :? e, Evil :? e) => Eff e Int Source #

nonscoped :: Eff e Int Source #