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

[Robin Green]

Miles Sabin <miles at milessabin.com> 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