> For the complete documentation index, see [llms.txt](https://frost-lang.gitbook.io/frost/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://frost-lang.gitbook.io/frost/security-features/memory-management.md).

# Memory Management

Frost combines manual memory management with modern safety features to provide developers with fine-grained control while minimizing the risk of memory-related errors.

## The `defer` Keyword

One of Frost's key memory management features is the `defer` keyword, which ensures that cleanup code is executed when leaving the current scope:

```frost
import "https://frost-lang.deno.dev/std/lib.ff"

main: never -> int = {
    buffer: *byte = malloc(1024)
    defer free(buffer)

    % Use buffer...

    0
} % buffer is automatically freed here
```

The `defer` keyword offers several advantages:

1. **Predictable Cleanup**: Cleanup code is placed near the allocation, improving readability.
2. **Error-Resistant**: Deferred actions are executed even if an error occurs, preventing resource leaks.
3. **Nested Deferral**: Multiple `defer` statements are executed in reverse order of declaration.

## LLVM Sanitizers

Frost leverages LLVM's powerful sanitizers to catch memory errors at runtime:

1. **AddressSanitizer (ASan)**: Detects out-of-bounds accesses, use-after-free, and memory leaks.
2. **MemorySanitizer (MSan)**: Finds uses of uninitialized memory.
3. **UndefinedBehaviorSanitizer (UBSan)**: Catches undefined behavior like integer overflow.

## Safe Abstractions

Frost provides safe abstractions over raw pointers:

```frost
% Array bounds checking
arr: [10]int = [1 2 3 4 5 6 7 8 9 10]
value: int = arr.#5 % Safe access

% Null pointer checks
if not ptr {
    printf("Null pointer detected\n")
}
```

## Best Practices

1. Use `defer` for all resource cleanup.
2. Leverage LLVM sanitizers during development and testing.
3. Implement custom destructors for complex types to ensure proper cleanup.

By combining these features, Frost provides a memory management model that is both powerful and safe, allowing developers to write efficient systems code with confidence.