tvl-depot/fun/aoc2019/default.nix

# Solutions for Advent of Code 2019, written in Emacs Lisp.
#
# For each day a new file is created as "solution-day$n.el".
{ pkgs, ... }:

let
  inherit (builtins) attrNames filter head listToAttrs match readDir;
  dir = readDir ./.;
  matchSolution = match "solution-(.*)\.el";
  isSolution = f: (matchSolution f) != null;
  getDay = f: head (matchSolution f);

  solutionFiles = filter (e: dir."${e}" == "regular" && isSolution e) (attrNames dir);
  solutions = map (f: let day = getDay f; in {
    name = day;
    value = pkgs.writeElispBin {
      name = "aoc2019";
      deps = p: with p; [ dash s ht ];
      src = ./. + ("/" + f);
    };
  }) solutionFiles;
in listToAttrs solutions