[Haskell-cafe] Happy outputs "parE" - ideas on what to change in my .y file?

Ulf Norell ulfn at cs.chalmers.se
Mon Jan 29 05:01:42 EST 2007

On Jan 27, 2007, at 11:11 AM, Mark Wassell wrote:

> Sometimes happy outputs 'parE' when I run it on my .y file? I  
> believe it is coming from a part of Grammer.lhs which has the  
> comment line
> "This bit is a real mess, mainly because of the error message  
> support."
> Are there any suggestions on what to change in my .y file to get  
> over this?

I've run into this problem as well (and submitted a bug report). You  
get the problem when there are undefined productions in your grammar.  
For instance:

%name parser Foo
Foo : Bar { () }

/ Ulf

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