If your job ad for a software developer states the language or tools you expect them to use after they start, you may be doing it wrong.

• Smart developers should be able to pick up almost any language quickly when they’re working together, particularly if they’re pair programming
• Smart developers are good programmers in whatever language they’re learning
• Smart developers who come to existing teams from different environments bring important skills from previous environments with them (for instance a .NET project team learning about migrations from a rails dev)

You are trying to hire developers that are Smart, and Get Things Done, aren’t you?

If you have a team full of XYZ developers, don’t try to just hire one more of them, you’re only increasing your mono-culture risk.

The goal is a performant team. Mono-culture can actually create risk around that.