Silly Type Families ∗ DRAFT

This paper presents an extension to standard Hindley-Milner type checking that allows constructors in data types to have non-uniform result types. We use Haskell as the sample language, [Hud92], but it should work for any language using H-M. It starts with some motivating examples and then shows the type rules for a simple language. Finally, it contains a sketch of how type deduction could be done.