My compiler/runtime/debugger/(memory visualizer/memory editor, not included in this video)

Quick explanation of what you can see here.
On the right is the code that got compiled (with an AST visualizer below).
On the left is a UI for all the types and functions that got generated.
Next to it are the generated instruction with an indicator for the current instruction pointer and a "speed" slider on top to run the instructions.
Next to that is just a print output and next to that is a visualization of the call stack.

When the code is run you can watch the instructions execute, the call stack grow and shrink, frame variables getting initialized and edited.
The "types" UI on the left also includes "Stack frame" types. You can imagine them as structs that describe the stack frames. When hovering over such "struct" members, they get highlighted in the stack frame visualization.

I will show the memory visualizer/editor another time. It's an interesting experiment as well.