I feel for the typical target market for Pony is going to be doing operations like that in floating point, or perhaps some explicit fixed-point non-integer type

I feel for the typical target market for Pony is going to be doing operations like that in floating point, or perhaps some explicit fixed-point non-integer type in financial cases. Whilst, yes, I can see this causing issues in some small subset of cases, the question really does come down to cost-benefit. Integer division by zero is not the only way for arithmetic to go wrong; would you expect every overflow to be checked too?