[Hugs-users] Pattern match failure leads to lots of output

[Ross Paterson]

On Fri, Sep 01, 2006 at 04:40:09AM +0100, Neil Mitchell wrote:
> Sometimes I get a pattern match error, with output such as:
> 
> pattern match failure: [...]
> 
> Where the output goes on forever. This is unfortunate, because having
> sped up the screen printing of WinHugs quite considerably, now its a
> race to hit the stop button before this stuff has taken up the whole
> screen buffer (100Kb) and pushed the name of the function causing the
> error off the top.
> 
> I guess the cause of this error is dictionary transformations
> resulting in a nested dictionary? Is there any way to stop this
> happening? Is it a known bug - it happens reasonably regularly to me.

It would probably be better to hide the dictionary arguments and the _vNNN
suffixes altogether in pattern match errors.  Can you put a boiled-down
example in the BTS?