[Nix-dev] [Haskell NG] Equivalent of the old eval "$configurePhase" && eval "$buildPhase" && eval "$checkPhase" ?
Peter Simons
simons at cryp.to
Fri Jan 23 08:57:54 CET 2015
Hi Mateusz,
>> Does http://permalink.gmane.org/gmane.linux.distributions.nixos/15524 help?
>
> Yes though it seems that we now need to update two files when making
> any changes: default.nix so that we can callPackage it in overrides
> and such (for example if it's a private package) and shell.nix so
> that we can enter sane environment.
I'm not sure what you mean. The number of files that you have to change
to accomplish non-standard behavior should not be different from what it
fwas before, i.e. the use of nix-shell certainly shouldn't have gotten
more complicated than it was. Could you please elaborate a little how
you've used nix-shell before and why that particular use-case won't now
work anymore?
> Previously we could simply cabal2nix into default.nix and from
> shell.nix callPackage ./. in simple case or add any extra shell-only
> settings in there. Now it seems that if I add a dependency I need to
> regenerate both files which is not fun if we have written any
> customisation. Am I wrong?
Previously, you generated a "default.nix" file with cabal2nix and ran
that from a hand-written "shell.nix" file. Why do you think that this
use-case is no longer possible? What exactly do you mean by
"re-generating both files"?
> Another downside is that manual use of Setup won't inherit flags
> specified in the expression: we manually have to --enable-testsuite
> whereas eval "$configurePhase" would do that for use when doCheck =
> true;.
It never occurred to me to configure interactive builds with the same
flags Nixpkgs uses, because the default builder sets options that I
wouldn't want ("--prefix=$out") while leaving out flags that I would
want ("--ghc-option=-j"). If you think this is important, then we can
define a shell variable in the interactive environment, say
$configureFlags, that you can pass to "./Setup" or "cabal" during the
configure phase. Would you like that?
Note that you can always use the old-style nix-shell approach and run
the default builder, i.e.:
$ cabal get haddock
$ cd haddock-2.15.0.2
$ nix-shell --pure ~/.nix-defexpr -A haskellngPackages.haddock
$ runHook setupCompilerEnvironmentPhase && runHook jailbreakPhase && runHook compileBuildDriverPhase
$ eval "$configurePhase" && eval "$buildPhase" && eval "$checkPhase"
We could also add the "runHook setupCompilerEnvironmentPhase ..." bit to
the "nix-shell" variable in the build environment so that these commands
are run automatically when you enter the interactive environment. Does
that sound useful?
I hope this helps,
Peter
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