nix-community.nixvim/modules/filetype.nix

{
  lib,
  helpers,
  config,
  ...
}:
with lib; let
  filetypeDefinition =
    helpers.mkNullOrOption
    (with types;
      attrsOf (
        oneOf [
          # Raw filetype
          str
          # Function to set the filetype
          helpers.rawType
          # ["filetype" {priority = xx;}]
          (listOf (either str (submodule {
            options = {
              priority = mkOption {
                type = int;
              };
            };
          })))
        ]
      ));
in {
  options.filetype =
    helpers.mkCompositeOption ''
      Define additional filetypes. The values can either be a literal filetype or a function
      taking the filepath and the buffer number.

      For more information check `:h vim.filetype.add()`
    '' {
      extension = filetypeDefinition "set filetypes matching the file extension";
      filename = filetypeDefinition "set filetypes matching the file name (or path)";
      pattern = filetypeDefinition "set filetypes matching the specified pattern";
    };

  config.extraConfigLua = helpers.mkIfNonNull' config.filetype ''
    vim.filetype.add(${helpers.toLuaObject config.filetype})
  '';
}