You can have an infinite loop, sure, but aside from that wasm semantics are precisely defined in a deterministic way (well, except for minor issues with float N

You can have an infinite loop, sure, but aside from that wasm semantics are precisely defined in a deterministic way (well, except for minor issues with float NaN bits). That is, if a computation terminates, it will always terminate and with the same results. That's the case because wasm itself has no way to tell the time, generate a random number, etc., and each operation's semantics are well-defined. (If infinite loops are a concern, you can do what wasm VMs do on the web which is to show a "stop script?" dialog after too much time passes.)