Deeply nested programs crash with a stack overflow while evaluating

[kms70847]

Consider the following program:

if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){if (True){
    print("OK.");
}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}

This should print "OK", but instead it crashes with a RecursionError.

This occurs because evaluate is naively recursive - in the worst case, it uses as much stack space as the maximum height of the abstract syntax tree.