top-level/impure.nix: refactor by removing 'with builtins'

pkgs/top-level/impure.nix

@@ -1,14 +1,13 @@
 /* Impure default args for `pkgs/top-level/default.nix`. See that file
    for the meaning of each argument. */
 
-with builtins;
 
 let
 
   homeDir = builtins.getEnv "HOME";
 
   # Return ‘x’ if it evaluates, or ‘def’ if it throws an exception.
-  try = x: def: let res = tryEval x; in if res.success then res.value else def;
+  try = x: def: let res = builtins.tryEval x; in if res.success then res.value else def;
 
 in
 
@@ -25,20 +24,20 @@ in
 , # Fallback: The contents of the configuration file found at $NIXPKGS_CONFIG or
   # $HOME/.config/nixpkgs/config.nix.
   config ? let
-      configFile = getEnv "NIXPKGS_CONFIG";
+      configFile = builtins.getEnv "NIXPKGS_CONFIG";
       configFile2 = homeDir + "/.config/nixpkgs/config.nix";
       configFile3 = homeDir + "/.nixpkgs/config.nix"; # obsolete
     in
-      if configFile != "" && pathExists configFile then import configFile
-      else if homeDir != "" && pathExists configFile2 then import configFile2
-      else if homeDir != "" && pathExists configFile3 then import configFile3
+      if configFile != "" && builtins.pathExists configFile then import configFile
+      else if homeDir != "" && builtins.pathExists configFile2 then import configFile2
+      else if homeDir != "" && builtins.pathExists configFile3 then import configFile3
       else {}
 
 , # Overlays are used to extend Nixpkgs collection with additional
   # collections of packages.  These collection of packages are part of the
   # fix-point made by Nixpkgs.
   overlays ? let
-      isDir = path: pathExists (path + "/.");
+      isDir = path: builtins.pathExists (path + "/.");
       pathOverlays = try (toString <nixpkgs-overlays>) "";
       homeOverlaysFile = homeDir + "/.config/nixpkgs/overlays.nix";
       homeOverlaysDir = homeDir + "/.config/nixpkgs/overlays";
@@ -46,25 +45,25 @@ in
         # check if the path is a directory or a file
         if isDir path then
           # it's a directory, so the set of overlays from the directory, ordered lexicographically
-          let content = readDir path; in
+          let content = builtins.readDir path; in
           map (n: import (path + ("/" + n)))
-            (builtins.filter (n: builtins.match ".*\\.nix" n != null || pathExists (path + ("/" + n + "/default.nix")))
-              (attrNames content))
+            (builtins.filter (n: builtins.match ".*\\.nix" n != null || builtins.pathExists (path + ("/" + n + "/default.nix")))
+              (builtins.attrNames content))
         else
           # it's a file, so the result is the contents of the file itself
           import path;
     in
-      if pathOverlays != "" && pathExists pathOverlays then overlays pathOverlays
-      else if pathExists homeOverlaysFile && pathExists homeOverlaysDir then
+      if pathOverlays != "" && builtins.pathExists pathOverlays then overlays pathOverlays
+      else if builtins.pathExists homeOverlaysFile && builtins.pathExists homeOverlaysDir then
         throw ''
           Nixpkgs overlays can be specified with ${homeOverlaysFile} or ${homeOverlaysDir}, but not both.
           Please remove one of them and try again.
         ''
-      else if pathExists homeOverlaysFile then
+      else if builtins.pathExists homeOverlaysFile then
         if isDir homeOverlaysFile then
           throw (homeOverlaysFile + " should be a file")
         else overlays homeOverlaysFile
-      else if pathExists homeOverlaysDir then
+      else if builtins.pathExists homeOverlaysDir then
         if !(isDir homeOverlaysDir) then
           throw (homeOverlaysDir + " should be a directory")
         else overlays homeOverlaysDir