Re: [jhc] Typechecker hiccup?

On Wed, Jul 18, 2007 at 09:45:19AM -0500, Samuel Bronson wrote:

On 7/17/07, John Meacham wrote:

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On Tue, Jul 17, 2007 at 10:20:01PM +0000, Samuel J. J. Bronson wrote:

...

I just tried to compile this program (based on figure one in "The GRIN Project: A Highly Optimising Back End for Lazy Functional Languages"):

{-# OPTIONS_JHC -N -fffi #-}

import Jhc.Basics import Jhc.Int import Jhc.Num import Jhc.Order

default (Integer, Double)

main = sum (upto 1 10)

upto m n | m > n = [] | otherwise = m : upto (m+1) n

sum [] = 0 sum (x:xs) = x + sum xs

And I got a stupid error about a missing "put" method for IORef. It seems that the typechecker isn't getting rid of all the MetaVars in this program...

hmm.. main not being an actual IO action doesn't behave too well with overloading. (I really should make it just fail without an explicit option saying you want to evaluate an expression)

I don't really want the code to work... I just want it to get a proper error.

Oh, yeah. that is what I meant to say. I just got sidetracked. In general, a lot of things that should be errors are not checked for. this can lead to badness later in the compilation process. It is unfortunate that there are still some user errors that are reported via a pattern match failure somewhere in the front end :) (but it is much better than it used to be)

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. 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.

I'd be happy with an error from the typechecker, an error from E.FromHs, an error from an E pass... pretty much anything before it's trying to write an .ho file ;-).

yes. certainly. John -- John Meacham - ⑆repetae.net⑆john⑈