06-operators.md

+++ title = "6. Operators" weight = 6 +++

6. Operators

Zen C supports operator overloading for user-defined structs by implementing specific method names.

Overloadable Operators

Category	Operator	Method Name
Arithmetic	+, -, *, /, %, **	add, sub, mul, div, rem, pow
Comparison	==, !=	eq, neq
	<, >, <=, >=	lt, gt, le, ge
Bitwise	&, |, ^	bitand, bitor, bitxor
	<<, >>	shl, shr
Unary	-	neg
	!	not
	~	bitnot
Index	a[i]	get(a, i)
	a[i, j]	get(a, i, j)
	a[i] = v	set(a, i, v)

Note on String Equality:

• string == string performs value comparison (equivalent to strcmp).
• char* == char* performs pointer comparison (checks memory addresses).
• Mixed comparisons (e.g. string == char*) default to pointer comparison.

Example:

impl Point {
    fn add(self, other: Point) -> Point {
        return Point{x: self.x + other.x, y: self.y + other.y};
    }
}

let p3 = p1 + p2; // Calls p1.add(p2)

Multi-Index Example:

struct Matrix {
    data: int[9];
}

impl Matrix {
    fn get(self, row: int, col: int) -> int {
        return self.data[row * 3 + col];
    }
}

let m = Matrix{data: [1,0,0, 0,1,0, 0,0,1]};
let val = m[1, 2]; // Calls Matrix.get(m, 1, 2)

Syntactic Sugar

These operators are built-in language features and cannot be overloaded directly.

Operator	Name	Description
|>	Pipeline	x |> f(y) desugars to f(x, y)
??	Null Coalescing	val ?? default returns default if val is NULL (pointers)
??=	Null Assignment	val ??= init assigns if val is NULL
?.	Safe Navigation	ptr?.field accesses field only if ptr is not NULL
?	Try Operator	res? returns error if present (Result/Option types)

|> Pipeline -- chain calls without nesting

fn double(x: int) -> int { return x * 2; }
fn add(a: int, b: int) -> int { return a + b; }

let res = 5 |> double |> add(10);
// Equivalent to: add(double(5), 10) → 20

?? Null Coalescing -- fallback for nullable pointers

let p: int* = NULL;
let default_val = &42;
let val = p ?? default_val;
assert(*val == 42);

??= Null Assignment -- assign only if NULL

let p: int* = NULL;
p ??= &42;
assert(*p == 42);

?. Safe Navigation -- access field without NULL check

struct Point { x: int; y: int; }
let p: Point* = NULL;
let x = p?.x;  // returns 0/default instead of crashing

? Try Operator -- short-circuit on error

import "std/result.zc"

fn try_work() -> Result<int> {
    let inner = may_fail();
    let val = inner?;  // returns Err early if inner is Err
    return Result<int>::Ok(val * 2);
}

Auto-Dereference: Pointer field access (ptr.field) and method calls (ptr.method()) automatically dereference the pointer, equivalent to (*ptr).field.