$> asc ... --runtime none

No runtime features at all. Useful for building low-level modules that do not require language features like managed classes, or if you'd like to compose your own runtime by including a custom memory allocator and garbage collector.

• No memory allocator
• No garbage collector

$> asc ...

The trace runtime adds support for dynamic memory management and garbage collection to your program.

• TLSF memory allocator
• ITCM garbage collector

$> asc ... --runtime arena

The arena runtime is just enough to make most language features work, but doesn't have sophisticated support for freeing memory. Useful when prototyping or for simple one-shot modules in that it produces very small modules with minimal overhead.

• Arena memory allocator with memory.reset()
• No garbage collector