nix-update.nvim

Dynamically and asynchronously update attributes of fetch-like constructions in Nix

Installation

Requirements

• nvim v0.9
• [Optional] nix-prefetch-url (and possibly more, checkout the included prefetchers here)

Lazy.nvim

{
    "reo101/nix-update.nvim",
    dependencies = {
        -- None (yet), but could use those
        -- "nvim-lua/plenary.nvim",
        -- "nvim-telescope/telescope.nvim",
    }
    config = function()
        require("nix-update").setup()
    end,
}

Configuration

Lua init file:

require("nix-update").setup(opts)

This setup function accepts the following table:

require("nix-update").setup({
  -- Extra prefetcher commands
  -- table of tables, where each one looks like this:
  extra_prefetcher_cmds = {
    ["myFetch"] = {
      -- (array of strings) Array of required system commands
      ["required-cmds"] = { "cmd1", "cmd2" },
      -- (array of strings) Array of required "fetch" keys
      ["required-keys"] = { "repo", "user" },
      -- (function) Function to run to generate a command
      ["prefetcher"] = function(opts)
        -- guaranteed to be non-nil
        local repo = opts.repo
        local user = opts.user
        -- extra (nonrequired/optional) keys, could be nil
        local submodules = opts.submodules

        -- has to return a table of `cmd` and `opts`
        return {
          cmd = "cmd1",
          args = {
            "wrapped_run",
            "--",
            "cmd2",
            repo .. "/" .. user,
          },
        }
      end,
      -- (function) Function to run to extract the new data
      ["extractor"] = function(stdout)
        -- array of lines from funning the corresponding command
        local first_line = stdout[1]

        -- has to return a table with new value for the keys
        return {
          version = "v." .. first_line
        }
      end,
    },
  },
})

NOTES:

• The table is empty by default
• required-cmds and required-keys are optional
• You can override the builtin definitions by using the same name in extra

Usage

Bind prefetch_fetch to a keymap:

-- <leader> -> Nix update -> under Cursor
vim.keymap.set("n", "<leader>nc", require("nix-update").prefetch_fetch)

Run it in a Nix file with the cursor inside a fetch:

let
  pname = "vim-fmi-cli";
  version = "0.2.0";
in {
  src = fetchFromGitHub {
    owner = "AndrewRadev";
    repo = pname;
    rev = "v${version}";
    sha256 = "sha256-SOMEOUTDATEDHASH";
  };
}

And nix-update will statically evaluate all string arguments to the fetch (string literals and interpolations), precalculate the correct hash and substitute it in the right place.

let
  pname = "vim-fmi-cli";
  version = "0.2.0";
in {
  src = fetchFromGitHub {
    owner = "AndrewRadev";
    repo = pname;
    rev = "v${version}";
    sha256 = "sha256-RAlvDiNvDVRNtex0aD8WESc4R/mAr7FjWtgzHWa4ZSI=";
  };
}

This updating mechanism allows for some pretty wild stuff, like this:

let
  pname = "vim-fmi-cli";
  version = "0.2.0";
  type = "256";
in rec {
  hash = "SOMEOUTDATEDHASH";

  src = fetchFromGitHub {
    owner = "AndrewRadev";
    repo = pname;
    rev = "v${version}";
    inherit sha256;
  };

  sha256 = "sha${type}-${hash}";
}

Running prefetch_fetch on this will figure out how to construct the current value of sha256 AND skip the common prefix when updating it, i.e. the sha256- part (consisting of the string sha, the value of type, a - and finally the value of hash, which are all scattered around lets and recs) and only update the hash variable to the correct suffix of the new sha256:

let
  pname = "vim-fmi-cli";
  version = "0.2.0";
  type = "256";
in rec {
  hash = "RAlvDiNvDVRNtex0aD8WESc4R/mAr7FjWtgzHWa4ZSI=";

  src = fetchFromGitHub {
    owner = "AndrewRadev";
    repo = pname;
    rev = "v${version}";
    inherit sha256;
  };

  sha256 = "sha${type}-${hash}";
}

I'm not really sure how often would this be of help but it's cool to have it nonetheless. 😄

Development

The lua folder is the compilation output of all files from the fnl directory. This is done using this Makefile:

make

You can clear the compilation output (the lua folder) using the clean subcommand:

make clean

NOTES:

• You have to have fennel (version 1.2.0) in your $PATH

Currently, there aren't any strict style guidelines being followed, except the ones derived from using Parinfer (through parinfer-rust)

TODO

• More commands
• More prefetchers
• Simpler prefetch commands (not just system ones, maybe lua functions)
• Style guidelines (with optional enforcement)
• Telescope pickers for selective updating
• Use plenary.nvim for running async commands instead of hand-rolled solution

Credits

• Original inspiration: https://github.com/jwiegley/nix-update-el
• The Fennel language: https://fennel-lang.org