anchor.diff:    # "y"] applied to some set e returns e.x.y, if it exists.  The
     # default value is returned otherwise.
     getAttr = attrPath: default: e:
  -    let {
  -      attr = head attrPath;
  -      body =
  -        if attrPath == [] then e
  -        else if builtins ? hasAttr && builtins.hasAttr attr e
  -        then getAttr (tail attrPath) default (builtins.getAttr attr e)
  -        else default;
  -    };
  +    let attr = head attrPath;
  +    in
  +      if attrPath == [] then e
  +      else if builtins ? hasAttr && builtins.hasAttr attr e
  +      then getAttr (tail attrPath) default (builtins.getAttr attr e)
  +      else default;
   
   
     # Filter a list using a predicate; that is, return a list containing
  
positive.code:       (hasSuffix "~" name)
      );
      in src: builtins.filterSource filter src;
  
  
    # Return a singleton list or an empty list, depending on a boolean
  
negative.code: 
  rec {
  
  
    # Identity function.
    id = x: x;
  
  
    # !!! need documentation...
    innerSumArgs = f : x : y : (if y == null then (f x)
  	else (innerSumArgs f (x // y)));
    sumArgs = f : innerSumArgs f {};
  