Unable to use this flake on darwin

[ashwinmathi]

I've tried both duplicating the haskell-template repo and starting with a fresh repo and adding the flake specified in this repo to no avail.

Upon running nix develop, it seems to properly download all the dependencies and stuff so after creating the flake.lock I get this error

error: flake 'path:/Users/$USER/Documents/Workspace/$PROJNAME' does not provide attribute 'devShells.x86-64-darwin.default', 'devShell.x86-64-darwin', 'packages.x86-64-darwin.default' or 'defaultPackage.x86-64-darwin' Did you mean one of devShells or x86_64-darwin?

From what I can tell the default package/devShell isn't getting set on darwin but I don't have any other operating systems to check this with.

The only resource I was able to find that helped me understand this a little more was this issue on the o.g. nix repo, but that seems to be pretty specific to the 'nix flake new' command which I'm not using for this. (EDIT: the proposed solution seems to be to use flake-utils whereas this flake uses flake-parts)

Is there something I should manually be changing to let this work on macOS?

Thank you for your time and energy maintaining this package!!

[srid]

Can you share your flake.nix? Do you have a project named "default"? Did you set "packages.default"?

What is your Nix version?

[ashwinmathi]

Nix Version: 2.11.1

I have an attribute "default" set in the haskellProjects sections if I'm understanding what you mean properly and yeah I have packages.default set here:

# flake.nix:
{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
    flake-parts.url = "github:hercules-ci/flake-parts";
    haskell-flake.url = "github:srid/haskell-flake";
  };
  outputs = inputs@{ self, nixpkgs, flake-parts, ... }:
    flake-parts.lib.mkFlake { inherit self; } {
      systems = nixpkgs.lib.systems.flakeExposed;
      imports = [ inputs.haskell-flake.flakeModule ];
      perSystem = { self', pkgs, ... }: {
        haskellProjects.default = {
          packages = { 
            # You can add more than one local package here.
            basic-package.root = ./.;  # Assumes ./basic-package.cabal
          };
          # buildTools = hp: { fourmolu = hp.fourmolu; ghcid = null; };
          # overrides = self: super: { };
          # hlintCheck.enable = true;
          # hlsCheck.enable = true;
        };
        # haskell-flake doesn't set the default package, but you can do it here.
        packages.default = self'.packages.basic-package;
      };
    };
}

[srid]

That looks right to me.

I have an M1 mac, and with Nix 2.11.0 https://github.com/srid/haskell-template works fine here.

Something about the string 'path:/Users/$USER/Documents/Workspace/$PROJNAME' in your error message looks odd. Anyway, I'd suggest two things:

• Create a github repo containing the minimal project whose nix develop errors out.
• Ask in Nix bug tracker or chat forum, as so far I don't see a reason to believe that this is unique to haskell-flake.

[ashwinmathi]

Gotcha, thanks so much for the help. Just to clarify I edited the original error message to make it more general so i took out my username and the projectname.

[ashwinmathi]

https://discourse.nixos.org/t/cant-use-nix-develop-on-x86-64-darwin/23205

Problem solved - just user error

[roberth]

nix flake show might reveal something, but first nix flake lock --update-input flake-parts, as I've just fixed nix flake show support.

[srid]

Be sure to make the systems list a singleton before doing this; eg.: systems = [ "x86_64-darwin" ];.

https://nixos.wiki/wiki/Haskell#IFD_and_Haskell