[Haskell-beginners] Convert my own types to the Haskell types using typeclass

Magnus Therning magnus at therning.org
Fri Apr 11 18:43:18 UTC 2014

On Fri, Apr 11, 2014 at 12:50:45PM -0400, ke dou wrote:
> instance Coercible (MyOption a) where
>   type Return (MyOption a) = Prelude.Maybe a
>   toHaskell (Some a) = Prelude.Just a
>   toHaskell None = Prelude.Nothing

The basic issue has been solved in another thread, but wouldn't you
want this one to be something like this:

instance Coercible a => Coercible (MyOption a) where
    type Return (MyOption a) = Prelude.Maybe (Return a)
    toHaskell (Some a) = Prelude.Just (toHaskell a)
    toHaskell None = Prelude.Nothing


Magnus Therning                      OpenPGP: 0xAB4DFBA4 
email: magnus at therning.org   jabber: magnus at therning.org
twitter: magthe               http://therning.org/magnus

What gets measured, gets done.
     -- Tom Peters
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