Did you check existing requests?

• I have searched the existing issues

Describe the feature

I would like to be able to pass a lua function to the formatter list by filetype. Either that or configure a custom formatter that is a lua function instead of an external command.

Provide background

I would like to run the following lua command when formatting go files:

vim.lsp.buf.code_action({
  filter = function(a)
    return a.kind == 'source.organizeImports'
  end,
  apply = true,
})

At the moment I can do this by having an extra check in my key binding but it would be nice to be able to run custom lua code as a formatter.

Current lazy.nvim solution:

return {
  'stevearc/conform.nvim',
  ...
  keys = {
    {
      '<leader>cf',
      function()
        if vim.api.nvim_buf_get_option(0, 'filetype') == 'go' then
          vim.lsp.buf.code_action({
            filter = function(a)
              return a.kind == 'source.organizeImports'
            end,
            apply = true,
          })
        end
        require('conform').format({ bufnr = 0, timeout_ms = 10000 })
      end,
      desc = 'Conform format',
    },
  },
}

What is the significance of this feature?

nice to have

Additional details

No response