I really like your remark about the performance of if (Contains("I", SplitWords(team))) so I added it to the README. If you don't want the 15 in the odds

I really like your remark about the performance of if (Contains("I", SplitWords(team))) so I added it to the README. If you don't want the 15 in the odds, just to this: auto goodOdds = without(15, keep_if(is_odd, numbers)); The fact, that `keep_if` does return a copy can easily obtained by looking at the function signature or the type of `odds`. Both things should not be complicated with a modern IDE. I agree with you in general. The library is not made for performance-critical stuff. But the "raw loops etc. are easier to understand by outsiders" seems like an argument agains using any libraries at all.