haskell: add more callPackageWithScope docs

This commit is contained in:
Benno Fünfstück 2017-04-25 14:44:10 +02:00 committed by Peter Simons
parent 731e0fa742
commit 6b36d26a24

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@ -44,6 +44,11 @@ self: let
mkDerivation = makeOverridable mkDerivationImpl;
# manualArgs are the arguments that were explictly passed to `callPackage`, like:
#
# callPackage foo { bar = null; };
#
# here `bar` is a manual argument.
callPackageWithScope = scope: fn: manualArgs:
let
# this code is copied from callPackage in lib/customisation.nix
@ -55,9 +60,16 @@ self: let
# info that callPackage uses to determine the arguments).
drv = if builtins.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (builtins.functionArgs drv) scope;
# this wraps the `drv` function to add a `overrideScope` function to the result.
drvScope = allArgs: drv allArgs // {
overrideScope = f:
let newScope = mkScope (fix' (extends f scope.__unfix__));
# note that we have to be careful here: `allArgs` includes the auto-arguments that
# weren't manually specified. If we would just pass `allArgs` to the recursive call here,
# then we wouldn't look up any packages in the scope in the next interation, because it
# appears as if all arguments were already manually passed, so the scope change would do
# nothing.
in callPackageWithScope newScope drv manualArgs;
};
in stdenv.lib.makeOverridable drvScope (auto // manualArgs);