classifier.nvim
Why?
This is a very, very simple mapping of ft to file extension and the other way around.
Should be used by plugin authors or users to glue together commands/plugins.
Caveats
Filetype to extensions is faster than extension to filetype. In order to avoid duplication, the extensions list is lazily populated.
Usage
local classifier = require("classifier")
-- Sample usage
local icons = require("nvim-web-devicons")
icons.get_icon(filename, classifier.ext(vim.bo.ft)[1])
-- another example
vim.fn.systemlist("rg --vimgrep -g '*.{" .. table.concat(classifier.fts(ft), ",") .. "}' -- " .. some_search)