[Haskell-cafe] deriving Data.HashTable - stack overflow

[Lyle Kopnicky]

Hi folks,

In GHC 7.6.3, the base Data.HashTable is deprecated, so I installed the
hashtables package. In order to work on your datatype, you need an instance
of Data.Hashable.Hashable.

So I went to the Data.Hashable page and looked up examples on how to derive
a Hashable instance for my datatype:
http://hackage.haskell.org/packages/archive/hashable/latest/doc/html/Data-Hashable.html

The problem occurs even when using the sample code on the page:


{-# LANGUAGE DeriveGeneric #-}

 import GHC.Generics (Generic)
 import Data.Hashable

 data Colour = Red | Green | Blue
               deriving Generic

 instance Hashable Colour

If I then type `hash Red` I get a stack overflow.

I am using the Haskell Platform, so I have hashable-1.1.2.5, but I notice
the docs are for hashable-1.2.0.10. If I install 1.2.0.10 though, other
code in my project breaks - seems like one part doesn't recognize the
instances from another part. So I'll stick with the platform version.

I am running the 32-bit Windows GHC 7.6.3. Haskell Platform 2013.2.0.0.

Any thoughts?

Thanks,
Lyle
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