ADA

So I've been noticing a lot of MoD/Aerospace jobs want people who know ADA, so I figure if I learn that language I may be able to fill a niche.

Discuss.

If you're having to figure out exactly what code is being called, you're doing it wrong. OO is intended as an abstraction. If I have a method that looks like:
def foo x
    x.bar
endWhat does that tell me about the type of x? That it understands the message "bar". That's all. Now if you wanted to restrict that further you could add type checking yourself.

If you don't know how to make use of powerful abstractions, that's fine, just stick with languages that don't provide them. Stay away from functional programming too.