Re: [Haskell-cafe] Decidable type systems? (WAS: Associated TypeSynonyms question)

Miles Sabin wrote:

Can someone explain to me why decidability is of any practical interest at all? procedure which might never terminate and one which might take 1,000,000 years to terminate? Actually, why push it out to 1,000,000 years: in the context of a compiler for a practical programming language, a decision procedure which might take an hour to terminate might as well be undecidable

But are there any decidable type checking algorithms that have been seriously proposed or used which would take far too long to terminate for real code? If not, then decidability is the only thing that matters. -- Robin