[Haskell-cafe] Are GADTs what I need?
maillist at kevinmahoney.co.uk
Mon Jul 13 06:41:25 EDT 2009
I'm currently writing an interpreter that I would like to be able to
use with other haskell programs. I would like to be able to pass along
arbitrary types though the interpreter. I've seen hints that GADTs can
do this, but I am having trouble understanding them.
So far, I've learnt you can do this:
data Value where
VInt :: Integer -> Value
VWrapper :: a -> Value
which can let you encode arbitrary 'dynamic' types into Value. I was
hoping to be able to pattern match to get the value out again e.g.
doSomething :: Value -> ....
doSomething (VWrapper String s) = .....
Also, anything that can help me out with GADTs in general will be much
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