nixpkgs/pkgs/build-support/mkshell/default.nix
Bas van Dijk cee35739ff mkshell: improve mergeInputs
mergeInputs is now simply defined in terms of `concatLists` and
`catAttrs` instead of a more complicated `foldr`.

Note that the order of PATH has also changed. For example running the
following with nix-shell:

  let
    pkgs = import <nixpkgs> {};

    shell1 = pkgs.mkShell {
      buildInputs = [ pkgs.htop ];
    };

    shell2 = pkgs.mkShell {
      buildInputs = [ pkgs.hello ];
    };

    shell3 = pkgs.mkShell {
      inputsFrom = [ shell1 shell2 ];
      buildInputs = [ pkgs.tree ];
    };

  in shell3

Results in the following PATH:

$ echo $PATH
...
/nix/store/yifq4bikf7m07160bpia7z48ciqddbfi-tree-1.8.0/bin:
/nix/store/vhxqk81234ivqw1a7j200a1c69k8mywi-htop-2.2.0/bin:
/nix/store/n9vm3m58y1n3rg3mlll17wanc9hln58k-hello-2.10/bin
...

Previously the order was:

/nix/store/n9vm3m58y1n3rg3mlll17wanc9hln58k-hello-2.10/bin
/nix/store/vhxqk81234ivqw1a7j200a1c69k8mywi-htop-2.2.0/bin:
/nix/store/yifq4bikf7m07160bpia7z48ciqddbfi-tree-1.8.0/bin:

I think the new order makes more sense because it allows to override
the PATH in the outermost mkShell.
2019-06-23 22:20:10 +02:00

46 lines
1.1 KiB
Nix

{ lib, stdenv }:
# A special kind of derivation that is only meant to be consumed by the
# nix-shell.
{
inputsFrom ? [], # a list of derivations whose inputs will be made available to the environment
buildInputs ? [],
nativeBuildInputs ? [],
propagatedBuildInputs ? [],
propagatedNativeBuildInputs ? [],
...
}@attrs:
let
mergeInputs = name: lib.concatLists (lib.catAttrs name
([attrs] ++ inputsFrom));
rest = builtins.removeAttrs attrs [
"inputsFrom"
"buildInputs"
"nativeBuildInputs"
"propagatedBuildInputs"
"propagatedNativeBuildInputs"
"shellHook"
];
in
stdenv.mkDerivation ({
name = "nix-shell";
phases = ["nobuildPhase"];
buildInputs = mergeInputs "buildInputs";
nativeBuildInputs = mergeInputs "nativeBuildInputs";
propagatedBuildInputs = mergeInputs "propagatedBuildInputs";
propagatedNativeBuildInputs = mergeInputs "propagatedNativeBuildInputs";
shellHook = lib.concatStringsSep "\n" (lib.catAttrs "shellHook"
(lib.reverseList inputsFrom ++ [attrs]));
nobuildPhase = ''
echo
echo "This derivation is not meant to be built, aborting";
echo
exit 1
'';
} // rest)