[jhc] Typechecker hiccup?

[Samuel Bronson]

On 7/18/07, John Meacham <john at repetae.net> wrote:

> >Also it's taking forever to compile the Prelude -- it's been
> > compiling all night and it's still on the same line of output as when
> > I went to bed... (I suspect that it would be on a different character
> > if I hadn't piped it through tee and less, though).
>
> Hmm.. this sounds wrong. it is possible there is an infinite loop
> somewhere. if you compile with some combination of -dcore -dcore-mini
> -dcore-steps -dcore-pass then you can usually find the culprit in these
> cases. you will see the same optimizations repeating over and over
> again. That is usually the cause.

No, it wasn't an infinite loop. It eventually finished (though it sure
took it's time writing the .ho file...). I think basically it has poor
locality of reference compiling such a large "module".

> Also, 'Show' and 'Read' instances for large data types tickle the
> simplifer in a way that makes it take way way too long. quadratic or
> even exponential behavior is sneaking in somewhere.

That doesn't surprise me.