[Jtsummers]

The point is that it's valid syntax (invalid syntax is found in an earlier phase of compilation and would report much faster). It's invalid in Swift's type system, and it takes it 42 seconds (in the string example) and 8 seconds (in the math expression one) for it to tell you that it can't type-check it in a reasonable time and then it quits.

[tantalor]

"Reasonable time" is subjective. What happens if you don't limit the time?

Guesses:

1. Successfully compiles

2. Reports an error

3. Never halts

4. Nobody knows