4 ms·
What version of GHC (or of the libraries) do you have? (Either String) should be a monad as specified through Control.Monad.Error: instance Error e => Mon
by shrughes 18y ago
What version of GHC (or of the libraries) do you have? (Either String) should be a monad as specified through Control.Monad.Error:
instance Error e => Monad (Either e) where
...
I didn't consider Data.Map.fromListWith; I didn't know about it. (Thanks.)