Because that wouldn't actually help. You couldn't optimize it for different
stringy types. Using instance overlap (which is evil), you *could* do
something similar.
class Monad m => MonadFail s m where
fail :: s -> m a
instance {-# OVERLAPPABLE #-} (MonadFail String m, IsString s) => MonadFail
s m where
fail = fail . toString
I don't think this is terribly likely to work well in practice.
On Tue, Nov 30, 2021, 2:16 PM Daneel Yaitskov
Dear Cafe,
MonadFail.fail takes String. I wasn't able to find MonadFail for custom error type. Is there any proposals to base?
Let's say Data.Text, which gains popularity with OverloadedStrings extensions.
class MonadFail m where fail :: String -> m a
Why not ? class MonadFail m where fail :: (forall s. IsString s => s) -> m a
class MonadFailWith m s where fail :: s -> m a
--
Best regards, Daniil Iaitskov
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