I used to require this, but after having spent many years programming this stopped being the case. I've reached the point where i can see a new abstraction and usually immediatly understand it, regardless of language.
Has your career taken you across many different programming paradigms?
A C programmer with no experience in concatenative or, especially, functional languages will have little chance of understanding code written in Forth or Haskell. They will have to start at the bottom of the learning curve.
The differences between languages aren't just skin-deep. Same goes for the design patterns in those languages. Haskell's applicatives have no analog in C, for instance.
You're not wrong, but those don't crack the top-10 of in-demand languages. Enough functional paradigms have also crept into more popular languages that you wouldn't be completely lost.
