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87d5e6fc1a
Before this change, a Dhall package like the Prelude would be
encoded as a record with one field per supported version. Then
downstream packages would specify which package to override
by selecting a different record field.
The problem with that approach is that it did not provide an
easy way to override a package to a version other than the default
ones supplied by Nixpkgs. Normally you would use the `.override`
method for this purpose, but the `override` method added by
`buildDhall{Directory,GitHub}Package` is clobbered by the
`override` method added by `callPackage` in
`./pkgs/top-level/dhall-packages.nix`.
The solution is to add a separate `.overridePackage` method which is
essentially the exact same as `.override`, except that it is no
longer clobbered by `callPackage`. This `.overridePackage` method
allows one to override the arguments supplied to
`buildDhall{Directory,GitHub}Package`, making it easier to specify
package versions outside of the ones supported by Nixpkgs..
This also includes a change to only build one (preferred) version of each
package (instead of multiple supported versions per package), in order to
minimize the maintenance burden for the Dhall package set.
25 lines
696 B
Nix
25 lines
696 B
Nix
{ lib }:
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let
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# This is essentially the same thing as `lib.makeOverridable`, except storing
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# the override method in a method named `overridePackage` so that it's not
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# shadowed by the `override` method added by `callPackage`
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makePackageOverridable = f: args:
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let
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result = lib.makeOverridable f args;
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copyArgs = g: lib.setFunctionArgs g (lib.functionArgs f);
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overrideWith =
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update: args // (if lib.isFunction update then update args else update);
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overridePackage =
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copyArgs (update: makePackageOverridable f (overrideWith update));
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in
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result // { inherit overridePackage; };
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in
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lib // {
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inherit makePackageOverridable;
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}
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