return is only an early exit

Since a block already hands back its last expression, you mostly won’t write return at all. It’s here for exactly one job: leaving a function early, before that last line.

fix sign = fn(n: Int): Int {
  if (n < 0) { return -1 };
  if (n > 0) { return 1 };
  0
};
sign(-4)

The two returns are guard clauses; fall past both and the final 0 is the normal result.

Recursion just works, too — a fix name is in scope inside its own definition, so a function can call itself:

fix factorial = fn(n: Int): Int {
  if (n <= 1) { 1 } else { n * factorial(n - 1) }
};
factorial(5)

factorial refers to factorial while it’s still being defined, and since the body only runs when it’s called, the name is ready by then. (Two functions that call each other — mutual recursion — is the one case this doesn’t cover yet.)