[Haskell-beginners] A Quantity Type - Integer without the Negative #'s

[aditya siram]

Hi all,
Is there a datatype in Haskell that can be used to represent only quantities
>= 0?  I got bitten by a bug because I forgot to reject an amount that was
below zero after applying a decrementing operator. A simple unit test would
have caught this, but I was wondering if there was some way of getting the
type system to ensure this.

thanks ...
-deech
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