Matt Godbolt sold me on Rust by showing me C++

Well, if you don't want to confuse parameters, you should use Objective-C.

You would do

[orderbook sendOrderWithSymbol:"foo" buy:true quantity:100 price:1000.00]

Cannot confuse that!

(I never used swift, I think it retains this?)

Swift does retain this, but it makes it look much more readable. The example above would be something like:

  orderbook.sendOrder(symbol: "foo", buy: true, quantity: 100, price: 1000.00);

It also has a nifty syntax for function declarations to allow decoupling the keyword from the variable name when that leads to more readable code:

  func parseInt(from s: String) -> Int {
    /* the variable is named 's' here */
  }

  parseInt(from: "123")