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Thu, 05 Feb 2015

All Perl 6 modules in a box

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Sometimes when we change things in the Perl 6 language or the Rakudo Perl 6 compiler that implements it, we want to know if the planned changes will cause fallout in the library modules out there, and how much.

To get a quick estimate, we can now do a git grep in the experimental perl6-all-modules repository.

This is an attempt to get all the published module into a single git repository. It is built using git subrepo, an unofficial git extension module that I've been wanting to try for some time, and that seems to have some advantages over submodules in some cases. The notable one in this case being that git grep ignores submodules, but descends into subrepos just fine.

Here is the use case that made me create this repository: Rakudo accesses low-level operations through the nqp:: pseudo namespace. For example nqp::concat_s('a', 'b') is a low-level way to concatenate two strings. User-level programs can also use nqp:: ops, though it is generally a bad idea, because it ties the program to the particular compiler used, and what's more, the nqp:: ops are not part of the public API, and thus neither documented in the same place as the rest of Perl 6, nor are there any promises for stability attached.

So we want to require module authors to use a pragma, use nqp; in order to make their use of compiler internal explicit and deliberate. And of course, where possible, we want them to not use them at all :-)

To find out how many files in the ecosystem use nqp:: ops, a simple command, combined with the power of the standard UNIX tools, will help:

$ git grep -l 'nqp::'|wc -l

That's not too bad, considering we have... how many modules/distributions again?

Since they are added in author/repo structure, counting them with ls and wc isn't hard:

ls -1d */*/|wc -l

Ok, but number of files in relation to distributions isn't really useful. So let's ask: how many distributions directly use nqp:: ops?

$ git grep -l nqp:: | cut -d/ -f1,2 |sort -u|wc -l

23 out of 282 (or about 8%) distributions use the nqp:: syntax.

By the way, there is a tool (written in Perl 6, of course) to generate and update the repository. Not perfect yet, very much a work in progress. It's in the _tools folder, so you should probably filter out that directory in your queries (though in the examples above, it doesn't make a difference).

So, have fun with this new toy!

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