String gives unbound variable error

[osbm]

Reproducing the behavior

Here is the related minimal example:

def max(a: u24, b: u24) -> u24:
  if a > b:
    return a
  else:
    return b

def collatz_len_and_peak(x: u24) -> (u24, u24):
  def go(n: u24, steps: u24, peak: u24) -> (u24, u24):
    if n == 1:
      return (steps, peak)
    else:
      if (n % 2) == 0:
        next = n / 2
      else:
        next = 3 * n + 1
      new_peak = max(peak, next)
      return go(next, steps + 1, new_peak)
  return go(x, 0, x)

def scan_upto(n: u24) -> (u24, u24, u24, u24):
  def scan_range(start: u24, end: u24) -> (u24, u24, u24, u24):
    if start > end:
      return (1, 0, 1, 0)
    elif start == end:
      (steps, peak) = collatz_len_and_peak(start)
      return (start, steps, peak, steps)
    else:
      mid = (start + end) / 2
      (best_n1, best_steps1, best_peak1, xor_steps1) = scan_range(start, mid)
      (best_n2, best_steps2, best_peak2, xor_steps2) = scan_range(mid + 1, end)

      def choose_best(steps1: u24, n1: u24, peak1: u24, steps2: u24, n2: u24, peak2: u24) -> (u24, u24, u24):
        if steps2 > steps1:
          return (n2, steps2, peak2)
        else:
          return (n1, steps1, peak1)

      (best_n, best_steps, best_peak) = choose_best(best_steps1, best_n1, best_peak1, best_steps2, best_n2, best_peak2)

      xor_steps = xor_steps1 ^ xor_steps2
      return (best_n, best_steps, best_peak, xor_steps)

  return scan_range(1, n)

def main() -> IO(u24):
  with IO:
    n = 1000000
    (best_n, best_steps, best_peak, xor_steps) = scan_upto(n)
    * <- IO/print(String.concat("n*=", String.from_num(best_n)))
    * <- IO/print("\n")
    * <- IO/print(String.concat("steps=", String.from_num(best_steps)))
    * <- IO/print("\n")
    * <- IO/print(String.concat("peak=", String.from_num(best_peak)))
    * <- IO/print("\n")
    * <- IO/print(String.concat("xor_steps=", String.from_num(xor_steps)))
    * <- IO/print("\n")
    return wrap(0)

I get this error:

In main.bend :
In definition 'main':
  Unbound variable 'String.concat'.
  Unbound variable 'String.from_num'.

Expected output is:

n*=837799
steps=524
peak=2974984576
xor_steps=880

This error seems very unrelated.

System Settings

Example:

• HVM: idk ?
• Bend: 0.2.37
• OS: Nixos
• CPU: i7-1065G7
• GPU: None
• Cuda Version None

Additional context

Trying to implement the same algorithm using multiple languages at the moment but massively parralel languages are a bit hard for me :(