REPL

Pick a small Codex program; it is compiled to IR and then to zig by the same native executables the ladder banks with, built into a native binary, and RUN. The last pane is the program's own output. No QEMU anywhere. The IR pane is pretty-printed; "full" links serve the raw artifact.

src      /home/steve/runs/20260823T163448Z-arena-4g/ladder
copied   2026-08-23T19:42:25Z
ladder   71a4a0f
codex    see sandbox MANIFEST
natives  0b43a67bc9ac

fib -- recursion, one printed number
eight queens, recursive -- the call stack holds the search; a dead branch returns empty and the caller tries the next column
eight queens, backtracking -- a tail-recursive cursor over one mutable board; retreat resumes right of the parked queen

Log in to run the compiler.

The program

Chapter: Fib

Section: Math
  fib : Integer -> Integer
  fib (n) =
   if n <= 1 then n
   else fib (n - 1) + fib (n - 2)

  double : Integer -> Integer
  double (n) = n + n

Section: Main
  opening : [Console] Nothing = act
   print-line-uni (show (fib 20))
  end

Codex source -> IR (bin/codexir)

(awaiting a run)

IR -> zig source (bin/zigemit)

(awaiting a run)

zig source -> native binary (zig build-exe)

(awaiting a run)

The program runs (./prog)

(awaiting a run)