It’s not an ideal example of partition-by anyway, because this particular input has all the values where the predicate returns true together. As you have shown,

It’s not an ideal example of partition-by anyway, because this particular input has all the values where the predicate returns true together. As you have shown, the result in this case is just to divide the list into the values that match the predicate and those that don’t. This is actually what the “partition” function does in some languages, including Haskell and Scala. However, in general, partition-by in Clojure does more than that and is more like a kind of split algorithm, which this example didn’t demonstrate. In any case, my point here was about syntax, so I used a standard and easily recognisable function in the other languages instead of getting bogged down in trying to reproduce the exact same behaviour. Apologies if this wasn’t clear.