[Nix-dev] How to version-bump haskell package in nix-shell?

[roconnor at theorem.ca]

I'll be curious as to what the offical answer is, but in the meantime the 
following somewhat akward expression appears to work:

haskellPackages.purescript.override (oldargs:
  { cabal = oldargs.cabal.override (oldargs:
    { extension = self: super: (oldargs.extension self super) //
      { version = "0.6.2";
        sha256 = "1zf2yyk3rdwk5992fhvqyd7b5w7mkzjcc0iyp75bscnjsggs31k0";
        buildDepends = super.buildDepends ++ [ haskellPackages.optparseApplicative ];
      };
    });
  })

Note that 0.6.2 has removed the dependency on cmdtheline and replaced it 
with optparseApplicative.  Filtering out cmdtheline from 
super.buildDepends can be done but it is so akward that I didn't bother. 
After all, having extra unused buildDepends isn't so terrible.

If you do go this route you'll probably want to abstract the above with a 
helper function that takes a derivation and your set of version, sha256, 
etc. overrides and does all this.  Maybe call it cabalOverride.

let cabalOverride = drv: newAttrs:
   drv.override (oldargs:
    { cabal = oldargs.cabal.override (oldargs:
      { extension = self: super:
         (oldargs.extension self super) // (newAttrs self super);
      });
    });
  in cabalOverride haskellPackages.purescript (self: super:
      { version = "0.6.2";
        sha256 = "1zf2yyk3rdwk5992fhvqyd7b5w7mkzjcc0iyp75bscnjsggs31k0";
        buildDepends = super.buildDepends ++ [ haskellPackages.optparseApplicative ];
      })

On Sun, 14 Dec 2014, Alex Berg wrote:

> I have a shell.nix file to give me a shell which has PureScript in it. I sometimes want to version-bump that. How do I do that? I pasted my shell.nix file at the bottom of this
> message, which includes a few attempts at doing this.
> 
> I see that boothead is doing what I want in his shell.nix [1], but not in the way I want to do it. He is redefining the *entire* package in a local file, but I want to just
> edit the "version" and "sha256" attributes of the central nix expression.
> 
> The "Modifying Packages" wiki page [2] says we can use an "override" attribute to add custom values to attributes, which sounds like exactly what I want to do. However, all the
> examples I see, including the "Haskell" wiki page [3], teach us to redefine the entire package in a local file. Surely we are also able to use the "override" attribute here,
> can't we? The "override" technique seems so much simpler and needs less boilerplate.
> 
> I did some source-code reading, which isn't fun, and I found a function called "makeOverridable" [4]. If we add that function to the cabal builder here [5], will this allow us
> to use this "override" technique?
> 
> If I add "stdenv.lib.makeOverridable" here, will I be able to do "haskellPackages.somePackage.override { version = "1.2.4" }" ?  
> 
> [1] https://github.com/boothead/purescript-nix/blob/master/shell.nix
> [2] https://nixos.org/wiki/Nix_Modifying_Packages#Overriding_Existing_Packages
> [3] https://nixos.org/wiki/Haskell#Maintaining_your_own_set_of_additional_Haskell_packages
> [4] https://github.com/NixOS/nixpkgs/blob/492dd14e78aebea0722dcb6becb2d6601ad51dc8/lib/customisation.nix
> [5] https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-support/cabal/default.nix#L312
> 
> 
> ----- shell.nix -----
> 
> { }:
> 
> with import <nixpkgs> {};
> 
> #let purescript = pkgs.stdenv.lib.overrideDerivation pkgs.haskellPackages.purescript ( oldAttrs : {
> #       src = {
> #               version = "0.6.2";
> #               sha256 = "";
> #       };
> #});
> let purescript = pkgs.haskellPackages.purescript.override {
>         version = "0.6.2";
>         sha256 = "";
> };
> #let haskellPackages = pkgs.haskellPackages.override {
> #       extension = self: super: {
> #               #purescript = self.callPackage ./purescript.nix {
> #               purescript = self.purescript.override {
> #                       version = "0.6.2";
> #                       sha256 = "";
> #                };
> #       };
> #};
> in rec {
>         pursEnv = stdenv.mkDerivation rec {
>                 name = "purescript-env";
>                 version = "1.1.1.1";
>                 src = ./.;
>                 buildInputs = [
>                         #haskellPackages.purescript
>                         purescript
>                         pkgs.nodePackages.grunt-cli
>                         pkgs.nodePackages.bower
>                         git
>                         which
>                         vim
>                         tree
>                         ];
>                 shellHook =
>   ''
>     echo "Patching NODE_PATH"
>     export NODE_PATH=$NODE_PATH:/nix/store/hhpwgi9k2j3c0r4q6rn0l0cf1r8vf98q-node-es5-ext-0.10.4/lib/node_modules
>   '';
>         };
> 
> 
>

-- 
Russell O'Connor                                      <http://r6.ca/>
``All talk about `theft,''' the general counsel of the American Graphophone
Company wrote, ``is the merest claptrap, for there exists no property in
ideas musical, literary or artistic, except as defined by statute.''