Reading the example, I really wish the syntax for push and pop had been "<foo" (push foo on stack) and ">bar" (pop from stack into bar). I find the choice of $ and ^ not obvious. Especially since, for me, ^ implies popping, not pushing.
I decided on using sigils and then my thought-process drifted to Perl/Php, so $ naturally felt like a variable definition (which naturally must pop from the stack). I guess ^ is “push ‘up’ to stack”. But it’s all really arbitrary irrelevant syntax. YMMV.