Is there a way to hide an existing data type so that I can use my own version?
Hi Folks, For learning purposes, I created an "Either" data type: data Either a b = Left a | Right b deriving (Show) However, when I try to use Left (or Right), I get an error message saying that it is ambiguous whether I am using Prelude.Left or Main.Left So I tried hiding Prelude.Either like so: import Prelude hiding Either But that produced an error. Is there a way to hide the existing Either data type so that I can use my own version? /Roger
On Tue, 31 Jul 2012 13:08:38 +0200, Costello, Roger L.
import Prelude hiding Either
That should be: import Prelude hiding (Either) Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --
Ah, excellent. Thanks Henk-Jan.
This works perfectly:
--------------------------------------------------------
import Prelude hiding (Either, Left, Right)
data Either a b = Left a | Right b
deriving (Show)
--------------------------------------------------------
/Roger
-----Original Message-----
From: Henk-Jan van Tuyl [mailto:hjgtuyl@chello.nl]
Sent: Tuesday, July 31, 2012 7:19 AM
To: beginners@haskell.org; Costello, Roger L.
Subject: Re: [Haskell-beginners] Is there a way to hide an existing data type so that I can use my own version?
On Tue, 31 Jul 2012 13:08:38 +0200, Costello, Roger L.
import Prelude hiding Either
That should be: import Prelude hiding (Either) Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --
participants (2)
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Costello, Roger L. -
Henk-Jan van Tuyl