Classes, enums, lists and match, in a program that

# shapes.zeno: classes, enums, lists and match, in a program that
# `zeno build` can compile.
#
#     zeno run examples/shapes.zeno      run it with the interpreter
#     zeno build examples/shapes.zeno    compile it to shapes.c and ./shapes
#     zeno build --llvm examples/shapes.zeno    the same through LLVM IR (shapes.ll)
#
# Open shapes.c afterwards: a class is a C struct, an enum is a struct with
# a tag and a union, and `match` is an if / else if chain on the tag.

import math

class Point {
    x: float
    y: float

    function distance_to(self, other: Point) -> float {
        return math.sqrt((self.x - other.x) ** 2 + (self.y - other.y) ** 2)
    }
}

enum Shape {
    Circle(centre: Point, radius: float)
    Rect(corner: Point, width: float, height: float)
    Nothing
}

function area(shape) {
    match shape {
        case Circle(_, r) { return math.pi * r * r }
        case Rect(_, w, h) { return w * h }
        case Nothing { return 0.0 }
    }
}

let origin = Point(0.0, 0.0)
let shapes = [Circle(origin, 1.0), Rect(Point(1.0, 1.0), 2.0, 3.0), Nothing]

var total = 0.0
for shape in shapes {
    print(f"{shape} has area {area(shape):.2f}")
    total += area(shape)
}
print(f"total {total:.2f}, biggest first: {[area(s) for s in shapes if area(s) > 4.0]}")
print(origin.distance_to(Point(3.0, 4.0)), shapes[2] == Nothing, len(shapes))

Circle(Point(x=0.0, y=0.0), 1.0) has area 3.14
Rect(Point(x=1.0, y=1.0), 2.0, 3.0) has area 6.00
Nothing has area 0.00
total 9.14, biggest first: [6.0]
5.0 true 3