The problem with those is they are

• either: hand-crafted parsers constructed to parse a specific language (HTML).

  These are no use because I'm looking for a parser constructor module.

• or: examples, of using the parser constructor module to construct a parser to parse some more or less complicated language, written by the author of the module that does the construction.

  It is unsurprising that the author of a given module is motivated enough, and reasonably adept at using his own module, to persist in getting something moderately complicated to work.

  But can anyone else?

If I could find an example of a parser module being used a) in a real-world project; b) of reasonable complexity; c) by some one other than its author; it would give some level of confidence that the module stands up to a) being learned; b) being debugged; c) being maintained in a timely fashion when bugs discovered through real-world usage are reported.

Of the 3 modules I've experimented with, they:

• had awful apis -- large, complicated, verbose -- with lousy documentation, often as not couched in so much academic/theoretical terminology as to be almost unintelligible.

  I want to use a parser; not learn about the theory behind them.

• gave almost useless error diagnostics when defining the grammar; and even worse diagnostics when given non-complaint source to parse.
• so ridiculously slow in operation that the are almost useless for real-world usage.
• produce parse tree so complicated you need to write another parser to process them.

A can see I am going to end up writing my own; but given the richness of the modules on cpan, I hoped that there was one amongst them that might stand up to RW usage.