[Haskell-cafe] Docs on the current and future constraint solver?

Simon Peyton-Jones simonpj at microsoft.com
Thu Jul 15 03:57:12 EDT 2010


| On 14 July 2010 18:39, Corey O'Connor <coreyoconnor at gmail.com> wrote:
| > I believe I have run headlong into issue #3064 in ghc
| > (http://hackage.haskell.org/trac/ghc/ticket/3064). All I think I know
| > is this:
| > * this is a performance issue with the system used to solve type
| constraints.
| > * the solver is undergoing an overhaul to resolve performance issues
| > in addition to other issues.
| > * An efficient constraint solver is difficult. NP-Complete in the general
| case?

It would be very helpful to have your code as a test case. Can you boil out a concrete program that demonstrates very poor performance of the type checker, and submit a Trac report?  That way we'll test the new type inference engine against it.  Lacking the example, we won't.  

Which is isn't a promise that we'll solve your problem -- but it's much easier to solve if we have a concrete example.  Many thanks!


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