Question

Here’s something I’ve seen in erlang code a few times, but it’s a tough thing to google and I can only find this example (the first code block in link below):

http://www.process-one.net/en/wiki/ejabberd_HTTP_request_handlers/

In the “head” of function definition of process/2

process(_LocalPath = ["world"], _Request) ->

there is a pattern match on first parameter / argument;

Does this act similarly like a guard, so the following clause will be executed only if the first argument passed to process/2 is string “world”, or is “world” some kind of a default argument? Or i completely misunderstood/ mis-guessed?

Answer 1

Yes, this is a pattern match. The clause will be executed if the first argument is a list with a single element, the element being the string “world”.