,

#!/bin/bash
#
# usage example:
#   $ , yarn --help
# This finds a derivation providing a bin/yarn, and runs it with `nix run`.
# If there are multiple candidates, the user chooses one using `fzy`.
set -euo pipefail

if [[ $# -lt 1 ]]; then
  >&2 echo "usage: , <program> [arguments]"
  exit 1
fi

argv0=$1; shift

attr="$(nix-locate --top-level --minimal --at-root --whole-name "/bin/${argv0}")"

if [[ "$(echo "${attr}" | wc -l)" -ne 1 ]]; then
  attr="$(echo "${attr}" | fzy)"
fi

nix run "nixpkgs.${attr}" -c "${argv0}" "$@"

default.nix

{ stdenv, fetchurl, nix-index, nix, fzy, makeWrapper }:

stdenv.mkDerivation rec {
  name = "comma";

  src = ./.;

  buildInputs = [ nix-index.out nix.out fzy.out ];
  nativeBuildInputs = [ makeWrapper ];

  installPhase = ''
    mkdir -p $out/bin
    cp , $out/bin/,
    chmod +x $out/bin/,
    wrapProgram $out/bin/, \
      --prefix PATH : ${nix-index.out}/bin \
      --prefix PATH : ${nix.out}/bin \
      --prefix PATH : ${fzy.out}/bin
  '';
}