Thanks, this is nice straightforward code that does what was asked. If I was basing my own use on this, I'd start by changing it somewhat to pass round arrayrefs rather than arrays (and therefore also to work through @a non-destructively with computed indices, rather than destructively with splice).

Then I'd probably pull try() inline to make it an inner loop, and wrap the whole thing in a function; at that point I think I'd have code pretty similar to BrowserUk's code below.

Hugo