[Haskell] Re: Type-Level arithmetic library

[Ashley Yakeley]

Robert Dockins wrote:
> While cleaning up my home directory, I discovered some code I worked  on 
> a while ago which implements type level arithmetic.

I know for the usual Peano representation of natural numbers, at least, 
it's possible to represent addition and subtraction with a single class 
with two fundeps (because classes represent relations between types 
rather than functions on them). See 
<http://haskell.org/haskellwiki/Peano_numbers>.