[Haskell-cafe] Restrict values in type

[Luke Clifton]

Hi Bob,

You can have a heterogeneous list of items that implement a typeclass if
> you have a wrapper that uses ExistentialQuantification. See
> http://www.haskell.org/haskellwiki/Heterogenous_collections
>

Hmm.. I'll take a closer look at that. It might be good enough, though I
would prefer to be able to pattern match on the elements in the list.

Regards,

Luke
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