Demo: Fibonacci

This demo generates Fibonacci numbers with the classic recursive recurrence: each value is the sum of the previous two, with base cases at 0 and 1. It illustrates branching recursion and builds a small prefix of the sequence so you can see the growth pattern directly in the output.

Related reading: Fibonacci number.

The fib function mirrors the mathematical recurrence directly: when n is 0 or 1 it returns immediately, otherwise it performs two recursive calls and adds their results. Instead of evaluating just one input, the demo computes a list from fib 0 through fib 10, which makes it easy to confirm correctness across multiple cases in one run.

fn fib : i32 -> i32 = \n ->
  if n <= 1
  then n
  else fib (n - 1) + fib (n - 2)

[fib 0, fib 1, fib 2, fib 3, fib 4, fib 5, fib 6, fib 7, fib 8, fib 9, fib 10]