Polymorphism

Polymorphic subroutines

Jai’s primary polymorphism mechanism is at the function level and is best described with an example.

sum :: (a: $T, b: T) -> T {
    return a + b;
}

f1: float = 1;
f2: float = 2;
f3 := sum(f1, f2);

i1: int = 1;
i2: int = 2;
i3 := sum(i1, i2);

x := sum(f1, i1);

print("% % %\n", f3, i3, x); // Output is "3.000000 3 2.000000"

When sum() is called, the type is determined by the T which is preceded by the $ symbol. In this case, $ precedes the a variable, and so the type T is determined by the first parameter. So, the first call to sum() is float + float, and the second call is int + int. In the third call, since the first parameter is float, both parameters and the return value become float. The second parameter is converted from int to float, and the variable x is deduced to be float as well.

THE ANY TYPE

Jai has a type called Any, which any other type can be implicitly casted to. Example:

print_any :: (a: Any) {
    if a.type.type == Type_Info_Tag.FLOAT
        print("a is a float\n");
    else if a.type.type == Type_Info_Tag.INT
        print("a is an int\n");
}