Dear parsing experts, I have been working on a medium-size parser using the PetitParser framework, which so far has been a very productive environment. But now I have a problem to which I could not find the solution in "Deep into Pharo", nor by searching around in the code. One of my production rules requires several parsed items to be equal. It should accept expressions such as 1 + 3 + 2 + 6 2 * 9 * 3 * 6 0 - 8 - 5 - 3 but not expressions that mix different operators (because my grammar has no precedence rules and thus requires parentheses for disambiguation). In various other parsing frameworks, I do this by parsing up to the first operator, retrieving it, and permitting only that same string in the following. But I haven't found a way to do this in PetitParser, nor any other obvious solution. The only solution I see right now is to have one production rule per operator, but that makes for a huge grammar. Is there another way? Thanks in advance, Konrad