Using stack 1.8.0 (the current `stack upgrade --git`) in NixOS?

Question

How does one obtain Stack 1.8.* on NixOS? In general, how does one ensure that the version of stack running on NixOS is the equivalent of the version that would run with stack update --git on a non-NixOS machine?

Answer 1

In Nix, if you want to have a specific version of a package, you create a derivation for it.

Derivation

To create the derivation for Stack, you can get one of the pre-built Stack releases using the nix-prefetch-scripts package and stdenv.mkDerivation as it is shown here.

Stack 1.8 seems not released yet, so you need to build it from sources. One way to do it is cabal2nix:

cabal2nix --shell 'https://github.com/commercialhaskell/stack.git' > stack.nix

There are more examples in the manual

nixpkgs

Now you have the derivation with the right version of the software. If you want it to be the system-default, you override your Nixpkgs.

Here is the example from the docs:

{
  packageOverrides = pkgs: rec {
    stack = ./path/to/stack.nix {};
  };
}

Update

We've found that the derivation produced by cabal2nix doesn't work in the case of stack because haskellPackages are missing some of the dependencies.

Here I've created gist with the (slightly adapted) result of running stackage2nix on the stack repo. The result of default.nix is not a single derivation but a set of packages required to build the stack. So the override for your system should look like:

{
  packageOverrides = pkgs: rec {
    stack = (import ./default.nix {}).stack;
  };
}