Re: [Haskell-cafe] Existential quantification of environments.

22 Nov 2005

      Am Dienstag, 22. November 2005 17:19 schrieben Sie:
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Wolfgang Jeltsch wrote:
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This seems to suggest:
Add a == exists (add :: a -> a -> a)
Doesn't "exists" normally quantify over types and not over values?
It is quantifying over types, it is saying there exists a type "a -> a -> a"
that has at least one value we will call "add"...
It says that there exists a value add.  With quantifying over types I meant 
something like this:

	exists a. <some type using the type variable a>

This is how forall in GHC and Hugs looks like.
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Best wishes,
Wolfgang