{ pkgs     ? import <nixpkgs> {},
  versions ? [ "8.10" "9.0" "9.2" "9.4" "9.6" "9.8" "9.10" "9.12" ],
}:
let
  inherit (builtins) attrValues replaceStrings;
  inherit (pkgs)     lib stdenv haskell;

  toPkg = version:
    "ghc" + replaceStrings ["."] [""] version;

  ghcs = lib.genAttrs versions
    (v: haskell.compiler.${toPkg v});

  mkLinkCmd = version: pkg: ''
    ln -s ${pkg}/bin/ghc $out/bin/ghc-${version}
    ln -s ${pkg}/bin/ghci $out/bin/ghci-${version}
    ln -s ${pkg}/bin/ghc-pkg $out/bin/ghc-pkg-${version}
  '';
in
stdenv.mkDerivation {
  name         = "multi-ghc";
  buildInputs  = attrValues ghcs;
  dontUnpack   = true;
  installPhase = lib.concatLines
    ([ "mkdir -p $out/bin" ] ++
     lib.mapAttrsToList mkLinkCmd ghcs);
}