MonadReader instance not found for RWST

[ethul]

I am not sure why the instance is not being picked up. The state and writer instances work just fine. The following example shows the issue when env <- ask is uncommented.

module Example.RWS where

import Prelude

import Control.Monad.Eff.Console
import Control.Monad.RWS.Trans
import Control.Monad.Reader (ask)
import Control.Monad.State (get)
import Control.Monad.Writer (tell)

import Data.Identity

testRWST :: RWST String (Array String) String Identity String
testRWST = do
  tell ["one"]
  tell ["two"]
  state <- get
  tell [state]

  -- No instance found for Control.Monad.Reader.Class.MonadReader _39
  -- (Control.Monad.RWS.Trans.RWST Prim.String (Prim.Array Prim.String) Prim.String Data.Identity.Identity)
  -- env <- ask

  pure "a"

main = do
  let see = runIdentity $ runRWST testRWST "env" "state"
  print see.log

Maybe I am missing something here?

[garyb]

I think you need to "do something" with env so a type can be inferred for it, so it's not left as _39.

[ethul]

I think you're right! Sorry about that. Looks like a non issue. Worked with:

env <- ask :: RWST String (Array String) String Identity String

[garyb]

I've been tripped up by that one so many times lately 😄

[ethul]

Definitely just tripped me up! Thanks for the help :)