&gt; But we also think with indices, and very intuitively, for anything involving a specific number of counts, like the example I gave (run 10 laps, I&#x27;ve run 1...5...7...8...10, done).<p>Counter-anecdote:<p>Oh, if people were good with indices, they wouldn&#x27;t have so much trouble with ordinals vs cardinals vs nominals.<p>&gt; And while this might be true for array like collections, I don&#x27;t think people have adapted &#x27;just fine&#x27; to map and filter on trees -- I very much doubt it&#x27;s commonly used at all.<p>Python&#x27;s set and dictionary comprehension encapsulate map, filter and cartesian product.  But that might strengthen your point: Python goes to great lengths to make these look like loops.<p>I guess we need to get a large number of ordinary people and do experiments on them.