[Nix-dev] [Nix-Dev] Problem building Haskell-lts2.21 (ghc784)

[Peter Simons]

Hi Sergey,

> What is correct way of adding specific versions of Haskell packages?

The user's manual has a section that demonstrates how to accomplish that:

  http://nixos.org/nixpkgs/manual/#how-to-override-package-versions-in-a-compiler-specific-package-set

Other sections of the manual have useful information about this subject,
too, so it might be worthwhile to read the whole chapter about Haskell.


> Why do we have both, say, 'transformers' and 'transformers_0_3_1' but
> only one (latest) version of many other pacakges, including
> hackage-security?

For every package, we ship the version suggested by LTS Haskell 7.x by
default. If Hackage happens to have a newer version, too, then we add
that as well. hackage-security is not part of LTS Haskell at all, so we
have only the latest version.

Best regards
Peter