DS can be negative

sample.md

while.janet

(defn f
  []
  (var i 32768)
  (while (pos? i)
    (when (= i 32768)
      (print "boo!"))
    (-- i)))

(comment

  (disasm f :bytecode)
  # =>
  '@[(ldc 1 0) 
     (push 1) 
     (ldc 3 1) 
     (call 2 3) 
     (jmpno 2 10) 
     (ldc 4 0) 
     (eq 3 1 4) 
     (jmpno 3 5) 
     (ldc 4 2) 
     (push 4) 
     (ldc 5 3) 
     (call 4 5) 
     (subim 1 1 1) 
     (jmp -12) 
     (retn)]

  (disasm f :constants)
  # =>
  @[32768 pos? "boo!" print]

  )

(defn main
  [& _]
  (getline "Press Enter to start.")
  (f))