Hello Thomas, Sunday, May 15, 2005, 7:26:11 PM, you wrote: TD> data SCode = SModule String [Export] | SUnknown TD> It would be useful to specify a function as so: TD> doSomethingToAModule :: SCode(SModule) -> SomeRandomOtherType because constructor names are globally unique, this can be written just as: doSomethingToAModule :: SModule -> SomeRandomOtherType i also needed similar feature, but to keep data as part of complex structure: data X = X { field1 :: SModule , field2 :: ... } if Haskell will allow to define new types by or'ing existing ones, whis will solve both our problems (modulo syntax sugar): data SModule = SModule String [Export] data SUnknown = SUnknown data SCode = SModule | SUnknown this extension will even allow to create ad-hoc polymorphic functions (!). but on other side - increased complexity and ambiguousity of type inferencing may be, adding only ability to "decompose" existing multi-variant types, but not to compose arbitrary types will not give such pressure on type inferencing system -- Best regards, Bulat mailto:bulatz@HotPOP.com