Why does Ruby expose symbols?

Question

Why does Ruby expose symbols for explicit use? Isn't that the sort of optimisation that's usually handled by the interpreter/compiler?

Answer 1

Part of the issue is that Ruby strings are mutable. Since every string Ruby allocates must be independent (it can't cache short/common ones), it's convenient to have a Symbol type to let the programmer have what are essentially immutable, memory-efficient strings.

Also, they share many characteristics with enum's, but with less pain for the programmer.

Answer 2

Ruby symbols are used in lieu of string constants in other similar languages. Besides the performance benefit, they can be used to semantically distinguish between string data and a more abstract symbol. Being syntactically different, they can clearly be distinguished in code.