Questions and answers

A collection of answers to questions that appeared over time.

What's the difference between an if/else and a select?

Semantically, a select differs from an if/else in that both alternatives are always executed, then picking one of them depending on the condition. So if one side has side effects, it is going to happen regardless of the condition. Performance-wise, a select (conditional move, works similar to a switch) is expected to be faster than an if/else where the condition is random (that is, branch prediction is not going to perform well) and the operands are cheap. An if/else where branch prediction is doing well, for example where checking a configuration value that is always the same, is expected to be fastest.

Does it support a main function?

Yes: By default, if no exported main function is present, any top-level logic is executed on module instantiation. If an exported main function, that is not generic or declared, is present, the compiler does not emit a (start ...) entrypoint and instead executes top-level statements when main is called.