[Haskell-cafe] Re: [Haskell] A puzzle and an annoying feature

Martin Sulzmann wrote:

[Discussion moved from Haskell to Haskell-Cafe]

Hi,

Regarding

- "lazy overlap resolution" aka unique instances

Well, if there's only instance which is not exported, then you can use functional dependencies.

Assume

class C a instance ... => C t

Internally, use

class C a | -> a instance ... => C t

But using functional dependencies feels like a sledge hammer, and it is also not Haskell 98. -- Lennart