[erlang-questions] Debugging yecc grammars: what techniques are available?

Mikael Pettersson mikpelinux@REDACTED
Sun Feb 5 11:18:39 CET 2017

Hugo Mills writes:
 >    I'm in the process of writing a domain-specific language, using a
 > custom lexer and a yecc parser. In the process of attempting to add a
 > new feature to the grammar, I've managed to break what appears to me
 > to be a completely unrelated piece of the grammar: I'm adding a
 > structure similar to a list comprehension, and suddenly the integer
 > comparison operators have stopped working in one group of cases.
 >    What approaches are there for debugging this kind of problem? The
 > best I can some up with is inspection of the .yrl source in detail,
 > but that's not helping. How else can I work out what the issue is?
 >    Obviously, I could post the grammar here for inspection by more
 > experienced minds than mine, but I'd prefer to find better tooling and
 > techniques rather than mere appeal to higher authority...

Caveat: while I have experience with various parsing techniques, including
LALR(1), I have none with the yecc tool.

Does yecc issue any warnings about shift/reduce or reduce/reduce conflicts?
If it does, you need to investigate those and resolve them.  With yacc and
bison it's possible to manually inspect the LALR(1) automaton for debugging.

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