Should exhaustiveness testing be on by default?

Simon Marlow marlowsd at gmail.com
Tue May 19 05:04:22 EDT 2009


On 19/05/2009 08:37, Simon Peyton-Jones wrote:
> No, the shortcomings are not documented I'm afraid.  It's a squishy question because when you add guards and view patterns it's undecidable whether patterns overlap or are exhaustive.

There are various open bugs regarding exhaustiveness/incompleteness 
though.  Start here:

   http://hackage.haskell.org/trac/ghc/ticket/595

and follow the links in the comments.  Also 
http://hackage.haskell.org/trac/ghc/ticket/2395 for view patterns.

Cheers,
	Simon

> Still, GHC's current implementation is poor.  It's a well-contained project that is awaiting a competent implementor. see http://hackage.haskell.org/trac/ghc/wiki/ProjectSuggestions
>
> Simon
>
> | -----Original Message-----
> | From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-
> | users-bounces at haskell.org] On Behalf Of Robert Greayer
> | Sent: 19 May 2009 04:00
> | Cc: glasgow-haskell-users at haskell.org
> | Subject: Re: Should exhaustiveness testing be on by default?
> |
> | On Mon, May 18, 2009 at 4:00 PM, Norman Ramsey<nr at eecs.harvard.edu>  wrote:
> |>  P.S. The exhaustiveness checker does need improvement...
> |
> | Is it documented somewhere what deficiencies the exhaustiveness
> | checker has (where it can report problems that don't exist or fails to
> | report problems that do...), and which deficiencies can't be resolved?
> |
> |
> | Rob
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