"Non-exhaustive patterns in case" error while parsing the BNFC file

0
votes

I am getting

bnfc: src/LexBNF.x:(80,13)-(86,20): Non-exhaustive patterns in case

error. What does it mean?

It doesn't really say what's wrong my BNF grammar, and I have no idea how to find the error. I tried looking for it for past few days, unsuccessfully.

I checked if every symbol is defined somewhere in the file, I fixed some rules, nothing helped.

2
bnfbnfc
Can you provide an example of the grammar+input that caused this error? – Grégoire

2 Answers

0
votes

I used to have 2.6, and had this same problem. However, on the tool's webpage, it says that some improvements about error messages have been made since earlier versions, so I installed the latest version (2.8), and that gave me a more informative error message. I'd recommend that you do the same.

-1
votes

Could be because you forgot the backslash on the grammar definition.

The link show a similar case: https://groups.google.com/forum/#!topic/proglang-course-2013/guL-rKm4Q_8