ML-style pattern matching is neat. There's actually an entire formal logic of computation oriented around it called the pattern calculus, though it's still in r

ML-style pattern matching is neat. There's actually an entire formal logic of computation oriented around it called the pattern calculus, though it's still in relatively early research. That said, the language with the most powerful pattern matching engine I've used so far has been Erlang. Just about everything there is intimately tied to it, giving it a homoiconicity between the code and the literal data types. You can even pattern match on binary formats, like file headers or packet structures. It seems like Algol-like languages are slowly absorbing lessons from ML. Rust is quite an evident example.