shell.nix

{ nixpkgs ? import <nixpkgs> {}, compiler ? "default" }:

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, adjunctions, base, concat-inline
      , concat-satisfy, constraints, containers, distributive
      , finite-typelits, free, ghc-prim, keys, newtype-generics, pointed
      , prettyclass, stdenv, transformers, vector-sized
      }:
      mkDerivation {
        pname = "concat-classes";
        version = "0.3.0.0";
        src = ./.;
        libraryHaskellDepends = [
          adjunctions base concat-inline concat-satisfy constraints
          containers distributive finite-typelits free ghc-prim keys
          newtype-generics pointed prettyclass transformers vector-sized
        ];
        description = "Constrained categories";
        license = stdenv.lib.licenses.bsd3;
      };

  haskellPackages = if compiler == "default"
                       then pkgs.haskellPackages
                       else pkgs.haskell.packages.${compiler};

  drv = haskellPackages.callPackage f {};

in

  if pkgs.lib.inNixShell then drv.env else drv