Is Ruby a functional language?

Question

Wikipedia says Ruby is a functional language, but I\'m not convinced. Why or why not?

Answer 1

It depends on your definition of a “functional language”. Personally, I think the term is itself quite problematic when used as an absolute. The are more aspects to being a “functional language” than mere language features and most depend on where you're looking from. For instance, the culture surrounding the language is quite important in this regard. Does it encourage a functional style? What about the available libraries? Do they encourage you to use them in a functional way?

Most people would call Scheme a functional language, for example. But what about Common Lisp? Apart from the multiple-/single-namespace issue and guaranteed tail-call elimination (which some CL implementations support as well, depending on the compiler settings), there isn't much that makes Scheme as a language more suited to functional programming than Common Lisp, and still, most Lispers wouldn't call CL a functional language. Why? Because the culture surrounding it heavily depends on CL's imperative features (like the LOOP macro, for example, which most Schemers would probably frown upon).

On the other hand, a C programmer may well consider CL a functional language. Most code written in any Lisp dialect is certainly much more functional in style than your usual block of C code, after all. Likewise, Scheme is very much an imperative language as compared to Haskell. Therefore, I don't think there can ever be a definite yes/no answer. Whether to call a language functional or not heavily depends on your viewpoint.