[Haskell-cafe] Maybe to Either -- is there a better way?
Max Rabkin
max.rabkin at gmail.com
Wed Aug 4 12:25:55 EDT 2010
On Tue, Aug 3, 2010 at 8:33 PM, Claude Heiland-Allen
<claudiusmaximus at goto10.org> wrote:
> {-# LANGUAGE TemplateHaskell, ScopedTypeVariables #-}
> import Language.Haskell.Djinn (djinnD)
> $(djinnD "maybeToEither" [t|forall a b . a -> Maybe b -> Either a b|])
> main = print . map (maybeToEither "foo") $ [Nothing, Just "bar"]
This is very cool (as is Djinn itself), but for me the ideal syntax would be
maybeToEither :: a -> Maybe b -> Either a b
maybeToEither = $(derived)
Is something like this possible in TH? The splice would have to know
its declared (even inferred?) type.
--Max
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