v3 VM + GC: Closures and Heap Objects

Why this module exists

Closures, arrays, and maps require heap allocation. The VM must track and reclaim memory explicitly with a mark-and-sweep GC.

1) Heap objects

Objects on the heap:

• arrays
• maps

Values store pointers to heap objects.

2) Mark-and-sweep

GC steps:

1. Mark reachable objects from roots
2. Sweep unreachable objects from the heap list

Roots include:

• VM stack values
• global and local environments
• captured environments inside closures

3) Closures

A closure value stores:

• the function bytecode
• a pointer to the environment where it was created

Calls create a new local scope whose parent is the closure environment.

4) Runtime errors

Dynamic type mismatches are runtime errors, not compile errors.