That may be true, but I languages can be taught and learned on the job, and frequently are. When giving an interview, you're generally more concerned with proce

That may be true, but I languages can be taught and learned on the job, and frequently are. When giving an interview, you're generally more concerned with processes, how the person thinks and solves problems, how they learn on the fly, etc. In each interview we give, we generally set them up for JS and PHP (we are a PHP shop), depending on the question but also give them the option of switching to a language they are more comfortable with. We can teach you PHP relatively easy; I came in with no PHP experience and was able to start building in Silex in under a month. What we care about is understanding basic architecture, database interaction, OOP principles, some design patterns, etc. So I think his choice to stick with what he knows and focus on learning algorithms was a good one. He could learn Java or Go or Ruby prior to the interview and then find out that he was placed on a project developing in Python, assuming he took the job. Languages are generally easy to learn and teach; best practices, algorithms, design patterns, etc. are what's hard.