[Nix-dev] A Journey into the Haskell NG infrastructure: Part I

[Mateusz Kowalczyk]

On 01/09/2015 10:27 PM, Thomas Hunger wrote:
> One thing that'd be useful is documenting how
> pkgs/development/haskell-modules/hackage-packages.nix is regenerated and
> how to fix common issues.
> 
> E.g. disabling tests done by overriding a package in
> haskell-modules/configuration-common.nix. But I don't understand how to
> retain a specific version of a package (e.g. you have time_1_5_0_1 in
> there, how did you do that?).
> 
> ~
> 

I second the request for a few words of how the nixpkgs collaborators
should now work with adding/fixing/updating/retaining the Haskell
package set. In the past it was cabal2nix the package, stick it in
libraries and add to haskell-packages.nix . What is it now?

> On 9 January 2015 at 18:11, Peter Simons <simons at cryp.to> wrote:
> 
>> Hi Thomas,
>>
>>  > I changed my sandbox code to look like the following. Is that how it's
>>  > intended to be used?
>>
>> yes, exactly. That's a very nice example. You can put that definition into
>> a
>> file, say shell.nix, and run
>>
>>   $ nix-shell --pure shell.nix
>>
>> to obtain an interactive environment that contains the compiler defined
>> above.
>>
>> If you want to go all out, you can also add a "shellHook" attribute to make
>> nix-shell define the magic environment variables that tell the 'ghc-paths'
>> package how to use your environment. For example:
>>
>>  | { pkgs ? (import <nixpkgs> {}).pkgs }:
>>  |
>>  | let
>>  |
>>  |   env = pkgs.haskellngPackages.ghcWithPackages (p: with p; [
>>  |     text mtl transformers warp cabal-install
>>  |   ]);
>>  |
>>  | in
>>  |
>>  | pkgs.stdenv.mkDerivation {
>>  |   name = "hello-world-wide-web";
>>  |   buildInputs = [ env ];
>>  |   shellHook = ''
>>  |     export NIX_GHC="${env}/bin/ghc"
>>  |     export NIX_GHCPKG="${env}/bin/ghc-pkg"
>>  |     export NIX_GHC_DOCDIR="${env}/share/doc/ghc/html"
>>  |     export NIX_GHC_LIBDIR=$( $NIX_GHC --print-libdir )
>>  |   '';
>>  | }
>>
>> Best regards,
>> Peter
>>
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>>
> 
> 
> 
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-- 
Mateusz K.