Comment by ufo

The stack's still there. I agree that reference manual's notation for how many values are pushed and popped can take a while to get used to, but at least it's straight to the point.

One trap with the stack is that it baits you into carefully sequencing the operations so that the output of one feeds into the input the the next. Sometimes values are popped far from the places that pushed them... It can be easier to reason about code that liberally copies the temporary values. Keep one stack slot for each "local variable" you want to work with. Then to work on them you copy that slot to the top, call the stack operation, and then write the result back to the appropriate stack slot.

Essentially, favor positive stack indices over negative indices, because the latter are more sensitive to the sequencing of your operations. Also, consider giving names to the stack indices instead of hardcoded numbers.