Languagetag: Language tag analysis

This project aims to support language tag parsing and analysis in Haskell, language tag meaning some code for identifying human languages. Currently it only includes the languagetag-bcp47 package, which supports BCP47-compliant language tag parsing and processing. The project may be updated in future to add support for other language tag resources, like ISO 639 or Glottolog.

Also included in the project is the languagetag-gen package, which generates certain types and functions in languagetag-bcp47 automatically from a local copy of the IANA subtag registry. It is an internal package, and you shouldn't need to use it unless you are developing languagetag-bcp47.

Current state of the packages

The languagetag-bcp47 package is currently mid-refactor, though it and the packages that are replacing it are reasonably usable as they are.

• The languagetag-bcp47-subtag package defines BCP47 subtags and provides parsers and Trie structures for them.
• The languagetag-bcp47-syntax package defines BCP47 language tags purely syntactically and provides parsers for them. These tags meet the "well-formed" level of standard compliance defined in BCP47, but may contain tags that don't have any registry-defined meaning.
• The languagetag-bcp47 package itself contains a complete copy of the current BCP47 registry rendered to individual Haskell records. It also provides types, parsers, and normalization and linting functions for these tags based on that copy of the registry. This should be renamed languagetag-bcp47-static, probably.
• The languagetag-bcp47-dynamic package defines tools for parsing the language tag registry. Hopefully in future (if I have time) it will contain tools for checking that tags meet the "vaild" level of standard compliance in BCP47 based on a dynamically-loaded copy of the registry, and also normalize and lint these tags based on such a registry. This package exists for two reasons: one, it will be used in a future rewrite of languagetag-bcp47-gen to clean that code up; and two, it will be a lighter alternative to languagetag-bcp47, since that package, and especially the internal Registry.Language module, is very large.

The refactor is still not quite done - notably, languagetag-bcp47-dynamic needs to be finished and languagetag-bcp47 needs to be rearranged a bit. Certain design decisions (regarding particular types, classes, even the package structure and organization) still need to be made as well, and I haven't had much free time recently to do any of this.