Why do Clojure vector function results exclude the stop value? [closed]

Question

Forgive me for the newb question and potentially incorrect terminology.

Clojure vector functions produce values that do not include the stop value. For example:

=> (subvec [:peanut :butter :and :jelly] 1 3)
[:butter :and]
=> (range 1 5)
(1 2 3 4)

The doc for range explicitly states this but doesn't give a rational: "...Returns a lazy seq of nums from start (inclusive) to end (exclusive)...".

In Ruby these operations are inclusive:

(1..5).to_a => [1, 2, 3, 4, 5] [:peanut, :butter, :and, :jelly][1,3] => [:butter, :and, :jelly]

Obviously these are very different languages, but I'm wondering if there was some underlying reason, beyond a personal preference by the language designers?

Answer 1

Making the end exclusive allows you to do things like specify (count collection) as the endpoint without getting an NPE. That's about the biggest difference between the two approaches.

Answer 2

It might be that the indexing was chosen in order to be consistent with Java libraries. java.lang.String.substring and java.util.List.subList both have exclusive-end indexes.