[Haskell-cafe] Unique Ordered Types

[Silvio Frischknecht]

Hi I'm experimenting with a unit system in haskell where users can add
"base units". I want to reduce units after multiplication and bring it
into a canonical form. The problem is what kind of types can the units have.

1)

data UnitA
data UnitB

Problem: They can't be ordered so UnitA * UnitB can be compared to UnitB
* UnitA, but I can't make a canonical form, which would make type
inference a lot better.

2)

type UnitA = Zero
type UnitB = Suc Zero

Problem: Now they can be ordered. But users can create conflicting
"basic units"



Silvio