rauhala.info/posts/guides/basic-nix-haskell.md

title	date
Nix and Haskell	2018-09-20

The simplest way you can use haskell and nix together is by calling callCabal2nix on the cabal file and using the resulting artifacts.

I usually create two files release.nix and default.nix. At least when developing, I avoid using the cabal2nix tool and instead let nix handle calling it for me. If I ever published an actual package, I would probably provide the autogenerated default.nix and nothing else.

Build instructions are managed by default.nix. At its simplest it's just a call to callCabal2nix, but might contain for example some extra cabal flags or adding patches.

# default.nix
{ haskellPackages }:

haskellPackages.callCabal2nix "foo" ./. {}

Pinning of haskell packages and system libraries are managed by this file. Nixpkgs requires a bootstrap <nixpkgs> in scope so that we can pin to a specific commit hash.

# release.nix
{ pkgs ? import <nixpkgs> {} }:

# No pinning yet
pkgs.callPackage ./default.nix {}