3 ms·

I think it's great that you can declare types optionally, but I think they are allowed for a different reason: documentation and explicitness. I would like Cry

• brigandish 6y ago
  I don't know if declaring all the types would speed up compilation, but what I do know is that they matter to the code itself. For instance, you can use them to overload methods: # version 1: def add(x : Int, y : Int) x + y end # version 2: def add(x : Number, y : Number) x + y end # version 3: def add(x : Number, y : String) x.to_s + y # convert a number to a string with to_s method end # version 4: def add(x, y) x + y end # new methods: # version 5: def add(x : Number, y : Bool) y ? x : 0 end # version 6: def add(x : String, y : String) if x.to_i? && y.to_i? add x.to_i, y.to_i # calls version 1 else x + y end end add(2, 3) # => 5 add(1.0, 3.14) # => 4.14 add("Hello ", "Crystal") # => "Hello Crystal" add(42, " times") # => "42 times" add 5, true # => 5 add 13, false # => 0 add("12", "13") # => 25 (also from the book) > I just feel that coming from Ruby to Rust, declaring types on function definitions is not that much of a hassle. I'm another one who doesn't understand why declaring types is seen as a hassle, but then I went from C# to Ruby so perhaps I was already used to it. Happy to bring a little back!