Special-purpose Damian modules that are useful for developing other modules or for solving difficult implementation problems, but which probably shouldn't be used directly in application code

That categorization looks rather odd to me. In what sense is a module you shouldn't use in production code good for "developing other modules"? Reading the code and getting inspired on how (not) to do things? Reading the code and understanding every bit and using those parts you absolutely can assert as being safe? Using that module in other modules you use in production code, thus using them indirectly?

TheDamian has given a hint in the BUGS section of that particular module:

There are undoubtedly serious bugs lurking somewhere in this code, if only because parts of it give the impression of understanding a great deal more about Perl than they really do.

OTOH many of the modules in that list are used heavily in production code (in the sense of CPAN modules being battle-tested, as dragonchild would have it :-) - Lingua::EN::Inflect comes to mind, Catalyst makes heavy use of Attribute::Handlers and NEXT, Hook::LexWrap is often recommended and so on. So, these modules might already be "battle tested" despite of any disclaimer they contain.

The general rules hold - don't use things you don't understand, because doing so leads to cargo cult code; read the docs and read the test suite: if your use cases fall within the boundary set up by those; if the bug list isn't too long and doesn't contain no-nos; if the module isn't alpha (i.e. hasn't too many moving parts), then it probably is production ready.

Of course, it depends on what you are producing and on your own notion of "production ready". What would be your answer?

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