lib: Use lib.fixed-points.extends to avoid repetition

Another attempt after my sloppy 48ccdf3. @infinisil, thanks again, reverted in 4794aa5 and explained my mistakes in 48ccdf3#commitcomment-29678643. I start with their work and provide this proof of this commit's correctness: ```nix (lib.fixedPoints.extends (lib.flip g) f) # now ((f: rattrs: self: let super = rattrs self; in super // f self super) (lib.flip g) f) # inline extends (self: let super = f self; in super // (lib.flip g) self super) # beta reduce (self: let super = f self; in super // g super self) # beta reduce (self_: let super = f self_; in super // g super self_) # alpha rename (self_: let super = f self_; in super // g super self_) # original, same ``` Eventually we might harmonize `overrideScope`'s `g` parameter with the general pattern, but I leave that breaking change as a separate step. Best not to refactor and break at once, and at least the abstractions make the oddity clearer.
NixOS · Aug 20, 2018 · 3cf4354 · 3cf4354
1 parent f8f6ab3
commit 3cf4354
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/lib/customisation.nix b/lib/customisation.nix
@@ -195,9 +195,10 @@ rec {
     let self = f self // {
           newScope = scope: newScope (self // scope);
           callPackage = self.newScope {};
+          # TODO(@Ericson2314): Haromonize argument order of `g` with everything else
           overrideScope = g:
             makeScope newScope
-            (self_: let super = f self_; in super // g super self_);
+            (lib.fixedPoints.extends (lib.flip g) f);
           packages = f;
         };
     in self;