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

Corey O'Connor coreyoconnor at gmail.com
Thu Jul 15 12:12:10 EDT 2010

On Wed, Jul 14, 2010 at 4:42 PM, Thomas Schilling
<nominolo at googlemail.com> wrote:
> The latest work is OutsideIn(X):
>  http://www.haskell.org/haskellwiki/Simonpj/Talk:OutsideIn
> This is quite long paper.  It describes a framework for
> constraint-based type inference and then instantiates it with a
> constraint solver that supports type families, GADTs and type classes.

Sounds like it's a long paper with good reason ;-) I will start
working my way through it.

Thanks for the information.

Corey O'Connor

> 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?
>> Beyond that I'm at a loss. What can I read to understand the
>> constraint satisfaction problem as it stands in GHC? Is there a paper
>> on the implementation of the current solver? Anything on how the new
>> solver will differ from the current?
>> I think I located one page on the new solver:
>> http://hackage.haskell.org/trac/ghc/wiki/TypeFunctionsSolving
>> Cheers,
>> Corey O'Connor
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> --
> If it looks like a duck, and quacks like a duck, we have at least to
> consider the possibility that we have a small aquatic bird of the
> family Anatidae on our hands.

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