Unsafe

Zap keeps raw pointer work behind explicit unsafe.

Compiler flag

Unsafe features must be enabled at compile time:

./zap/build/zapc --allow-unsafe program.zp

Unsafe blocks

fun main() Int {
    var value: Int = 41;

    unsafe {
        var ptr: *Int = &value;
        *ptr = *ptr + 1;
    }

    return value;
}

Unsafe functions

unsafe fun deref(ptr: *Int) Int {
    return *ptr;
}

Pointer fields

struct Box {
    ptr: *Int
}

Supported low-level operations

• address-of with &value
• raw pointer types like *Int and *Void
• dereference with *ptr
• pointer arithmetic such as ptr + i
• casts with as
• manual allocation through std/mem

Allocation example

import "std/mem";

fun main() Int {
    unsafe {
        var ptr: *Int = mem.malloc(3 * 8) as *Int;
        if ptr == null {
            return 1;
        }

        *ptr = 10;
        *(ptr + 1) = 20;
        *(ptr + 2) = 30;

        mem.free(ptr as *Void);
        return 0;
    }
}

Use unsafe sparingly. The point is explicit escape hatches, not making the whole language unchecked by default.