(
  ; core utilities
  ($x ^x ^x)          $dup
  ($_)                $drop
  ($x $y ^x ^y)       $swap
  ($a $b $c ^b ^a ^c) $rot
  (sub)               $-
  (0 swap - -)        $+
  (())                $nil
  (nil eq)            $null?
  ($x x)              $force
  (10 emit)           $cr

  ; recursion via y-combinator
  ($f ($x (^x x) f) dup force) $Y ($g (^g Y)) $rec

  ; if-stmt
  ($c $t $f c ^f ^t rot cswap $_ force) $if
  ($f $t $c $fn ^f ^t ^c fn)     $endif

  ; range
  ($self $body $start $end
    ^if (^start ^end eq) nil
      (^start body ^end ^start 1 + ^body self)
    endif
  ) rec $do

  70 65 ^emit do cr
)