[Nix-dev] overriding a package

[Catonano]

I am following this guide to override a package

https://nixos.org/wiki/Nix_Modifying_Packages#Overriding_Existing_Packages

I copied and pasted the example about the "mu" and "mySed" packages and I
ended up with this



    {
     packageOverrides = pkgs: rec {

       # Create a new package, "myDrRacket", which is identical to an
       #   existing package, "racket", but uses a different version.
       myRacket = pkgs.stdenv.lib.overrideDerivation pkgs.racket (oldAttrs:
{
         pname = "InfTaRacket";
     version = "6.1.1.8";
     #name = "${pname}-${version}";
         src = fetchurl {
           url =
http://www.cs.utah.edu/plt/snapshots/current/installers/racket-6.1.1.8-src.tgz
;
           sha256 =
"c9b4b634cdda62841739ed41179ed3daf42b7231cd024d8d3a7b39cfe0e44fc3";
         };
         patches = [];
       });
     };
   }

The result is

nix-env -i InfTaRacket
error: undefined variable ‘fetchurl’ at "/home/me/.nixpkgs/config.nix":14:16
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.science.uu.nl/pipermail/nix-dev/attachments/20150131/cb3c1030/attachment.html