The function you presented that trims to the right has quadratic runtime behavior if your string has a long sequence of spaces that is not at the end of the str

The function you presented that trims to the right has quadratic runtime behavior if your string has a long sequence of spaces that is not at the end of the string. For example, "a b". A similar performance bug was behind a 30 minute downtime at stackoverflow.com, because a code snippet with 20 thousand spaces inside a comment showed up on their frontpage. See, its not that simple :) http://lua-users.org/wiki/StringTrim http://lua-users.org/wiki/StringTrim Anyway, I wasn't trying to say bad things about Lua with my examples. Its just that if you go to any large Lua project out there there is a very good chance you will find some "utils" module in there with yet another reimplementation of a lot of these common functions. Ideally we should have people reusing more stuff from Luarocks than they are right now.