Re: [Haskell-cafe] How do I lift Control.Monad.Reader.local?

Hi David, I believe the easiest way to do what you want is to use MonadReader class instead of explicit t (Reader [String] a): push' :: MonadReader [String] m => String -> m a -> m apush' s = local (s:) Best, Nick 2013/10/31 David Fox

I can write a stack push function in the reader monad like so:

import Control.Monad.Reader

push :: String -> Reader [String] a -> Reader [String] a push s action = local (s :) action

How can I write a push that works inside a monad transformer?

push' :: MonadTrans t => String -> t (Reader [String]) a -> t (Reader [String]) a push' s action = ???

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