{ lib, ... }:
with lib;
with builtins; rec {
  readLines = f: filter (s: (isString s) && s != "") (split "\n" (readFile f));
  splitWhitespace = s: filter isString (builtins.split "[[:space:]]+" s);
  abs = i: if i >= 0 then i else i * -1;
  delta = x: y: abs (x - y);
  noop = x: x;
  listSum = foldl' add 0;
}