pyrox.dev / nixpkgs
lol
fork atom

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

Another attempt after my sloppy https://github.com/NixOS/nixpkgs/commit/48ccdf322d9e7a68d0caf5833511ee3e53ec7d3a.

@Infinisil, thanks again, reverted in https://github.com/NixOS/nixpkgs/commit/4794aa5de233b5bf2d1c3245946379699d023467 and explained my mistakes in https://github.com/NixOS/nixpkgs/commit/48ccdf322d9e7a68d0caf5833511ee3e53ec7d3a#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.

John Ericson 3cf43547 f8f6ab3e

options
unified split
Changed files
+2 -1
lib
customisation.nix
+2 -1
lib/customisation.nix 
···

       
195

       
195

       
 

       
    let self = f self // {


     

       
196

       
196

       
 

       
          newScope = scope: newScope (self // scope);


     

       
197

       
197

       
 

       
          callPackage = self.newScope {};


     

       

       
198

       
+

       
          # TODO(@Ericson2314): Haromonize argument order of `g` with everything else


     

       
198

       
199

       
 

       
          overrideScope = g:


     

       
199

       
200

       
 

       
            makeScope newScope


     

       
200

       

       
-

       
            (self_: let super = f self_; in super // g super self_);


     

       

       
201

       
+

       
            (lib.fixedPoints.extends (lib.flip g) f);


     

       
201

       
202

       
 

       
          packages = f;


     

       
202

       
203

       
 

       
        };


     

       
203

       
204

       
 

       
    in self;