Nix-based Unison Development Environment

shell.nix

# this file is consumed by `nix-shell` to provide ghc+stack, as well as whatever development tools you need
# hlint is provided as an example

# this file can and should be customized with whatever development tools you want to use.

let
  pkgs = import <nixpkgs> { };
in
  pkgs.mkShell {
    # include build or development tools here
    buildInputs = [ pkgs.stack pkgs.ghc pkgs.haskellPackages.hlint ];
  }

stack-shell.nix

# this file is consumed by stack + nix to provide the right libraries for the unison build. it can probably be left alone.

{ ghc }:
with (import <nixpkgs> {});

let
  libs = [
    gmp
    ncurses
    zlib
  ];
  native_libs = lib.optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
    Cocoa
    CoreServices
  ]);

in haskell.lib.buildStackProject {
  inherit ghc;
  nativeBuildInputs = native_libs;
  buildInputs = libs;
  name = "unisonBuildEnv";
  src = if lib.inNixShell then null else ./.;
}

stack.yaml

# ...

# add the following stanza to your stack.yaml to tell stack to build dependencies using nix.

nix:
    enable: true
    shell-file: stack-shell.nix
    
# alternatively, create a separate file like stack-nix.yaml, and invoke stack with `stack --stack-yaml stack-nix.yaml ...`