release.nix: use extend instead of override

release.nix

@@ -35,8 +35,7 @@ let
         "ihaskell-static-canvas"
         "ihaskell-widgets"
       ]);
-  haskellPackages = nixpkgs.haskell.packages."${compiler}".override {
-    overrides = self: super: {
+  haskellPackages = nixpkgs.haskell.packages."${compiler}".extend (self: super: {
     ihaskell          = nixpkgs.haskell.lib.overrideCabal (
                         self.callCabal2nix "ihaskell" ihaskell-src {}) (_drv: {
       preCheck = ''
@@ -51,9 +50,7 @@ let
     haskell-src-exts  = self.haskell-src-exts_1_20_2;
 
     static-canvas     = nixpkgs.haskell.lib.doJailbreak super.static-canvas;
-
-    } // displays self;
-  };
+  } // displays self);
   ihaskellEnv = haskellPackages.ghcWithPackages (self: [ self.ihaskell ] ++ packages self);
   jupyter = nixpkgs.python3.withPackages (ps: [ ps.jupyter ps.notebook ]);
   ihaskellSh = cmd: extraArgs: nixpkgs.writeScriptBin "ihaskell-${cmd}" ''