I don't see in what way exceptions can be considered to be side effects? The fact that they return in a 'differently-structured' manner doesn't really matter, nor what you call the abstraction that happens to throw/signal/return them, right?
Unexpected, perhaps - less strict than just disallowing them. And that's not really feasible either: prove that OOM can't happen? JVM bugs? Interrupts? Never-returns? That said, something that might be useful would be a utility type in the stdlib that could express 'more functional' typing for method results; perhaps 'ResultOrException<R>'. Or just 'ResultOrFail<R, F>' - might allow more structured/tighter failure types than just an exception. Or ResultOrFailOrExn<R, F>. Big design space. On Fri, Dec 19, 2025 at 2:50 PM Robert Engels <[email protected]> wrote: > > I’ll disagree with the last case. The number one reason functional > programming is a mess is because people don’t exclusively use it with pure > functions. Errors or Exceptions are side effects. You can map them to a value > and try and call it a function but it’s not. Use map/reduce with pure > functions and it works fine. > > On Dec 19, 2025, at 3:37 AM, Alex Otenko <[email protected]> wrote: > >
