feat: support tables as keys in setup({ formatters_by_ft })

[drowning-cat]

require('conform').setup({
  -- You can use tables as keys to define multiple file types for the same formatter config
  [{ "bash", "csh", "ksh", "sh", "zsh" }] = { "beautysh" },
  -- Simple keys always override tables as keys, regardless of order
  bash = { "shfmt" },
})

There is only one caveat: lua-language-server currently does not support type annotations for table keys.
See LuaLS/lua-language-server#2610 for more details.

[stevearc]

I appreciate the work that went into this, but I'm not interested in adding this syntax to setup. I have intentionally tried to make the interface as simple and stupid as possible, I've actually removed some old features because they complicated the API. It's easier to learn, easier to read, and is a hard guard against scope creep. I've had issues with my other plugins where feature request upon feature request causes the config options to explode. My current stance is that if it's something that can reasonably be done in the end-user config, it should be. Given that this is just a small bit of syntactic sugar to save a few lines, I don't think it's worth adding.

[tanishqmanuja]

I am using this, would this cause any issues down the line .. asking because what's in the commit utils looks different

function flatten_formatters(formatter_table)
    local flattened = {}
    
    for key, value in pairs(formatter_table) do
        if type(key) == "table" then
            -- Handle multiple (table)
            for _, filetype in ipairs(key) do
                flattened[filetype] = value
            end
        else
            -- Handle single (string)
            flattened[key] = value
        end
    end
    
    return flattened
end

[drowning-cat]

@tanishqmanuja

Don't worry, there should be no problem except in very rare cases where you mutate formatters_by_ft directly, as they will link to the same object. For example:

table.insert(require('conform').formatters_by_ft[<ft>], <additional-formatter>)

If you want to prevent this, simply make a deep copy of the value:

for _, filetype in ipairs(key) do
  flattened[filetype] = vim.deepcopy(value)
end

[tanishqmanuja]

@drowning-cat,

Thanks for the detailed explanation and clarity on table references, really appreciate it!

I am a js dev so still drawing parallels between it and lua 😅