[Haskell-cafe] RE: RFE: Extensible algebraic user-defined data types?

[Henning Thielemann]

On Fri, 29 Apr 2005, Simon Peyton-Jones wrote:

> | Regarding reusing constructor names across several datatypes: is it
> | possible to qualify them with their enclosing datatype name, like
> | Maybe.Nothing where there is a name conflict? Then I might reuse
> | Nothing in my hypothetical data type, and it would be NEither.Nothing
> | if conflicting with Maybe.Nothing
>
> This is one of those features that's hard to evaluate: modest gain in
> expressiveness, and modest increase in complexity.

For people sticking to the scheme that each module implements one 
principal data type, give prefix-less function, accessor, and constructor 
names and call them by qualification, the need for such a feature is 
reduced.