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I want to be able to write

x :: Eff (reader :: Reader Int, maybe :: Maybe) Int x = do config <- ask -- configuration from (Reader Int) monad just config -- using (Maybe) Monad runX :: Int runX = runPure (runMaybe doIfNothing (runReader 6 x)) -- outputs: 6

using the Eff Monad

Is this possible to do using Eff?

If not how can we make it work not using Eff?

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You can use the MaybeT and ReaderT monad transformers on top of Eff, but you cannot match the two in the way you wrote above:

import Prelude import Data.Maybe import Control.Monad.Eff import Control.Monad.Eff.Class import Control.Monad.Eff.Console import Control.Monad.Maybe.Trans import Control.Monad.Reader.Trans x :: ReaderT Int (MaybeT (Eff (console :: CONSOLE))) Int x = do liftEff (log "Asking...") config <- ask pure config main :: Eff (console :: CONSOLE) (Maybe Int) main = runMaybeT (runReaderT x 6)
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I don't like monad transformers, Iv'e seen some talks where something like Purescript's Eff monad was used with monads like Reader, but I don't know if it's possible to do in Purescript, maybe we need to define a new monad similar to Eff.

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