Is Ruby a functional language?

I most definitely think you can use functional style in Ruby.

One of the most critical aspects to be able to program in a functional style is if the language supports higher order functions... which Ruby does.

That said, it's easy to program in Ruby in a non-functional style as well. Another key aspect of functional style is to not have state, and have real mathematical functions that always return the same value for a given set of inputs. This can be done in Ruby, but it is not enforced in the language like something more strictly functional like Haskell.

So, yeah, it supports functional style, but it also will let you program in a non-functional style as well.

Ruby isn't really much of a multi-paradigm language either, I think. Multi-paradigm tends to be used by people wanting to label their favorite language as something which is useful in many different areas.

I'd describe Ruby is an object-oriented scripting language. Yes, functions are first-class objects (sort of), but that doesn't really make it a functional language. IMO, I might add.

Ruby is a multi-paradigm language that supports a functional style of programming.