Re: [Nix-dev] development environments
The overlay dumps the hackage package information into a .nix file. Then a nix code tries to determine dependencies based on (eventually patched) cabal file contents creating the .nix derivations on the fly depending on what you asked for. Because brute force is used only a limited set of haskell package versions is used when resolving dependencies. Advantage: Very often it just works. Disadvantage: If it does not it still requires some debugging and patching. Depeding on cadal flags the right dependencies are chosen automatically. Eg if you have foo-1.0 dependencies: if flag-A LIB_IF else LIB_ELSE Then either LIB_IF or LIB_ELSE will be passed as build input depending on flag configuration. Darcs on its own has more than 8 flags, thus there are 2**8 different ways to configure it (not counting slightly different versions in the dependencies). Thus in theory its strong enough to find a working configuration, but in the real world there are too many ways, which is why its me setting sane defaults. Because the whole dependency chain is calculated on the fly its possible to inject your own dev version of a packages: Eg make darcs depend on bytestring-my- version. Because dependencies are calculated on the fly, and the end result is only a script you install into a directory specific profile you can have multiple profiles. source ./ghc-6.0-setup # then compile with ghc-6.0 2nd shell: source ./ghc-7.x-setup # then compile with ghc-7.x Thus testing multiple configurations at the same time using different shells is made easy. Because I don't do much Haskell at the moment the hackage dump I created is a couple of month old. If you're interested I can show you how to update it yourself. Marc Weber ___ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev
Re: [Nix-dev] development environments
Excerpts from Lucas Paul's message of Fri Feb 22 21:13:54 +0100 2013: I'm just learning how to make software in nix (with some help from the wiki). If I want to use an IDE, say Leksah, should that be in the build environment too, or should I install that into my default profile? build environment, because leksah uses ghc internal features, such depends on your build env such as ghc version AFAIK. Of course if you use the same set of libraries always, installing it into your default profile may be more convenient. Maybe try both, and keep using what works best for you. At this point in time I also want to remind that there is a second way for install haskell packages using nixpkgs https://nixos.org/wiki/Nixpkgs-haskell-overlay Marc Weber ___ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev
Re: [Nix-dev] development environments
I found the Haskell overlay interesting, but I'm left with only a vague idea about what problem it's solving, and how. It mentioned darcs as an example, but I didn't grasp the difference between installing darcs with and without the overlay. Could you elaborate a bit? On Sat, Feb 23, 2013 at 1:02 AM, Marc Weber marco-owe...@gmx.de wrote: Excerpts from Lucas Paul's message of Fri Feb 22 21:13:54 +0100 2013: I'm just learning how to make software in nix (with some help from the wiki). If I want to use an IDE, say Leksah, should that be in the build environment too, or should I install that into my default profile? build environment, because leksah uses ghc internal features, such depends on your build env such as ghc version AFAIK. Of course if you use the same set of libraries always, installing it into your default profile may be more convenient. Maybe try both, and keep using what works best for you. At this point in time I also want to remind that there is a second way for install haskell packages using nixpkgs https://nixos.org/wiki/Nixpkgs-haskell-overlay Marc Weber ___ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev ___ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev
