Demo: Factorial

This demo computes n! using direct recursion: it multiplies n by the factorial of n - 1 until it reaches the base case 0, which returns 1. It is a minimal example of structural recursion over integers and shows how a simple mathematical definition maps directly to Rex function syntax.

Related reading: Factorial.

The implementation is centered on fact, which uses an if expression to separate the base case from the recursive case. The final line evaluates fact 6, so the output is a single integer result; this keeps the demo focused on call structure and termination rather than data modeling.

fn fact : i32 -> i32 = \n ->
  if n == 0
  then 1
  else n * fact (n - 1)

fact 6