This is the output of compiling "fac.txt"

// factorial

fac(n){
  if( n == 0 ) return 1;
  else return n * fac(n-1);
}

main(){
  print(fac(3));
}
-----------------------
The parse-tree looks like:

fac
main
(fun main (print (call fac 3 )))
(fun fac (else (== #1 0 )(return 1 )(return (* #1 (call fac (- #1 1 ))))))
------------------------
Now the linear-code:

;; fun main, arity 0, fs 0
:fun1
  lit.3
  call fun2
  print
  ret

;; fun fac, arity 1, fs 1
:fun2
  local.1
  lit.0
  eq
  jf L101
  lit.1
  ret
  jmp L102
:L101
  local.1
  local.1
  lit.1
  sub
  call fun2
  mul
  ret
:L102
  ret