Operator Overloading and Overriding

[Alexius-Huang]

What?
Operator overloading which extends more usage of operator

Why?
Methods and functions can be overloaded, why not also for operators.

How?
Important rules: Operators which forbidden to overload/override are=, => and |> (see #67 )

def +(op1: Str, op2: Str): Str do
  op1.concat(op2)
end

def +(op1: Str, op2: Num): Str => op1 + op2.toStr()
def +(op1: Num, op2: Str): Str => op2 + op1

foo = "123" + "456"
bar = "123" + 456
baz = 123 + "456"

override def +(op1: Num, op2: Num): Num => op1 - op2
bazz = 123 + 456

Compiled Result

function OP_plus_1(op1, op2) {
  return op1.concat(op2);
}

function OP_plus_2(op1, op2) {
  return op1.concat(op2.toString());
}

function OP_plus_3(op1, op2) {
  return OP_plus_2(op2, op1);
}

const foo = OP_plus_1("123", "456");
const bar = OP_plus_2("123", 456);
const baz = OP_plus_3(123, "456");

function OP_plus_0$1(op1, op2) { // compiled result might change because of default function name
  return op1 - op2;
}

const bazz = OP_plus_0$1(123, 456);

[Alexius-Huang]

It would be better to solve issue #76 first then implement operator overloading, since operator can really get confused with method invocation.