Pattern matching as is in Erlang, or how it is in most modern languages, was not there at some point and was considered novel and exotic. Now most everyone can

Pattern matching as is in Erlang, or how it is in most modern languages, was not there at some point and was considered novel and exotic. Now most everyone can do [X, Y | _] = [1, [2], 3, 4] and it's not a seen as something advanced. I am not sure if it was ever called "unification" in Erlang, it was always called "pattern matching". But the equal sign did retain its name as the "match" operator: https://www.erlang.org/doc/system/expressions.html#the-match-operator-and-the-compound-pattern-operator https://www.erlang.org/doc/system/expressions.html#the-match.... And that is a legacy of Prolog. I never read X=1 as "make X equal to 1", in my head I always read it as "match X to 1". At some point, I also wondered: why didn't they go all the way and just bring in Prolog's full unification. They obviously liked Prolog; Erlang was developed in Prolog initially, even. Well, it turns out with unification we'd have to carry the match "hole" around until we might a match. But Erlang has lightweight processes with isolated heaps which communicate via messages, so now we'd need to pass these "holes" around from process to process until say one of the processes somewhere manages to unify the value, and then have it propagate across the system to original query. That breaks isolation. So you see how the two neat features came into a conflict and they picked one over the other, and rightly so it seems.