extensible-effects- An Alternative to Monad Transformers

Safe HaskellSafe



Example usage of Control.Eff



newtype TooBig Source #

The datatype for the example from the paper. See the tests for the example


TooBig Int 


runErrBig :: Eff (Exc TooBig ': r) a -> Eff r (Either TooBig a) Source #

specialization to tell the type of the exception

sum2 :: Member (Reader Int) r => Member (Reader Float) r => Eff r Float Source #

Multiple Reader effects

writeAll :: Member (Writer a) e => [a] -> Eff e () Source #

Write the elements of a list of numbers, in order.

sumAll :: (Num a, Member (State a) e) => [a] -> Eff e () Source #

Add a list of numbers to the current state.

writeAndAdd :: (Member (Writer a) e, Member (State a) e, Num a) => [a] -> Eff e () Source #

Write a list of numbers and add them to the current state.

sumEff :: Num a => [a] -> a Source #

Sum a list of numbers.

lastEff :: [a] -> Maybe a Source #

Safely get the last element of a list. Nothing for empty lists; Just the last element otherwise.

lastAndSum :: Num a => [a] -> (Maybe a, a) Source #

Get the last element and sum of a list

data Move x where Source #


Move :: Move () 

handUp :: Eff (Move ': r) a -> Eff r a Source #

handDown :: Eff (Move ': r) a -> Eff r a Source #