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Thanks. Type inference for types of rank > 2 is undecidable, how does this go together with the claim that Frege has type inference? I'm not a Haskell expert,
by mafribe 11y ago
Thanks.
Type inference for types of rank > 2 is undecidable, how does this go together with the claim that Frege has type inference?
I'm not a Haskell expert, but I think the
{-# LANGUAGE RankNTypes #-}
extension enables HRTs in Haskell too.
- voxfrege 11y agoType inference for higher ranks is in fact undecidable, but not type checking. Hence, exactly like in Haskell with RankNTypes, you need to annotate your higher rank functions. Actually, the Frege compiler employs an algorithm described in Simon Peyton-Jones paper "Practical Type Inference for Higher Ranked Types". Ordinary HM types are inferred, and higher ranked types checked.
- mafribe 11y agoThanks. It's great to have basically Haskell on the JVM. I'll give it a try.