One thing to take into consideration when looking at candidates is also their perfered language/style. Idiomatic programmers tend to solve problems in the style of their prefered language. I learned to solve basic programming problems with various languages in classroom settings. My first real-world programming experience was in Perl. I started off programming in a language-neutral style. The logic was all the same, only the syntax changed for the language.

As I gained experience and competency, my coding style began to take on a very Perl-centric style. When I found myself forced to code in Java, I was extremely frustrated by the Java way and longed for my map and grep.

In the process of hiring Perl engineers, I can tell that a person is a Java programmer if they solve a very simple Perl problem in an over-engineered Java manner. My current position requires me to maintain code that was written by a C++ developer. The system architecture fails to take advantage of some of Perl's OO features in favor of a far more restrictive C++ style implementation.

The bottom line is this: If you don't mind the thought of potentially maintaining C++ or Java-style Perl, pay no attention to the candidate's prefered language; only look at their knowledge base. If you want someone that is going to write Perl-style Perl, hire a Perl developer. If the candidate does not have all of the experience that you are looking for, but has a proven track record of quickly learning new technologies, you can feel confident that they will fill in the areas that they lack with relative speed as compared to breaking the Java programmer of the habit of seeing everything as an object.