Nix Flakes

hey folks, is it possible to have multiple devShells for a platform? for example, one with glibc and one with musl under linux?

22:21:46

Yep, the flake schema is devShells.x86_64-linux.X

23:04:46

      devShells.x86_64-linux = {
        clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
          packages = [ pkgs.hello ];
        };
        gcc = pkgs.mkShell {
          packages = [ pkgs.cmatrix ];
        };
      };

23:11:05

devShells.${system} is an attrset

23:11:17

what's the musl stdenv that I don't know

23:11:59

In reply to @kranzes:matrix.org

      devShells.x86_64-linux = {
        clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
          packages = [ pkgs.hello ];
        };
        gcc = pkgs.mkShell {
          packages = [ pkgs.cmatrix ];
        };
      };

Where's pkgs coming from there?

23:21:53

let binding

23:22:08

nixpkgs instantiation?

23:22:10

inputs.nixpkgs.legacyPackages.x86_64-linux

23:22:30

👌 Just wanted to be sure whether devShells behaves differently

23:22:46

{
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

  outputs = inputs:
    let
      system = "x86_64-linux";
      pkgs = inputs.nixpkgs.legacyPackages.${system};
    in
    {
      devShells.${system} = {
        clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
          packages = [ pkgs.hello ];
        };
        gcc = pkgs.mkShell {
          packages = [ pkgs.hello ];
        };
      };
    };
}

23:23:14

really basic flake for 1 system architecture

23:23:37

Pretty cool. Thanks folks

23:31:13

hey friends, I have a very basic flake that follows. when i do nix flake show I get error: expected a derivation. Where might be the error? is there any way to get a traceback?

11:04:36

  description = "A very basic flake";

  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
    flake-utils.url = github:numtide/flake-utils;
  };

  outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
        rec {
          devShells.${system} = {
            clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
              packages = [ pkgs.hello ];
            };
            gcc = pkgs.mkShell {
              packages = [ pkgs.hello ];
            };
          };
        }
    );
}

11:04:47

*

  description = "A very basic flake";

  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
    flake-utils.url = github:numtide/flake-utils;
  };

  outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
        rec {
          devShells.${system} = {
            clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
              packages = [ pkgs.hello ];
            };
            gcc = pkgs.mkShell {
              packages = [ pkgs.hello ];
            };
          };
        }
    );
}

11:05:01

*

  description = "A very basic flake";

  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
    flake-utils.url = github:numtide/flake-utils;
  };

  outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
        rec {
          devShells.${system} = {
            clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
              packages = [ pkgs.hello ];
            };
            gcc = pkgs.mkShell {
              packages = [ pkgs.hello ];
            };
          };
        }
    );
}

11:05:14

*

 {
  description = "A very basic flake";

  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
    flake-utils.url = github:numtide/flake-utils;
  };

  outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
        rec {
          devShells.${system} = {
            clang = pkgs.mkShell.override { stdenv = pkgs.clangStdenv; } {
              packages = [ pkgs.hello ];
            };
            gcc = pkgs.mkShell {
              packages = [ pkgs.hello ];
            };
          };
        }
    );
}

11:06:31

That's a flake-utils moment. Omit the ${system} part from devShells.

12:25:13

devShells.${system} -> devShells

12:25:24

flake-utils handles the genAttrs part for the outputs

12:25:53