[Haskell-cafe] types and braces

Niklas Broberg niklas.broberg at gmail.com
Wed Apr 15 14:27:07 EDT 2009

Hi Conor,

Conor McBride:
> The trouble is, the production I've added causes a
> reduce/reduce conflict in the grammar, but I don't get
> any more precise complaint than that.

To get more precise complaints, you should give the -i flag to happy,
that will cause happy to print the whole parser table into a file
named Parser.info. It also tells you in which states the conflicts
occur, allowing you to track 'em down.

> I guess what I'd like to know is whether I just need to
> debug my grammar extension, or whether the notation I'm
> proposing actually introduces a serious ambiguity that
> I'm too dim to notice. I'm mostly sending this in the
> hope that I have one of those "d'oh" moments you
> sometimes get when you articulate a stupid question in
> public.

I don't immediately see what the clash in that context would be - I
*think* what you propose should be doable. I'd be interested to know
what you come up with, or I might have a look at it myself when I find
a few minutes to spare.



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