gistfile1.txt

    data IntList = nil | cons(int,IntList)

is sugar for

    enum IntListCon { nilCon , consCon };
    struct IntList { IntListCon con ; int head ; IntList* tail; };

    struct IntList nil;
    nil.con = nilCon;

    struct IntList cons(int x, IntList* xs) {
      struct IntList xs';
      xs'.con = consCon;
      xs'.head = x;
      xs'.tail = xs;
      return xs';
    }

and

    case xs of {
      nil -> f
      cons(x,xs') -> g
    }

is sugar for

    if (nilCon == xs.con) {
      f
    } else if (consCon == xs.con) {
      int x = xs.head;
      IntList* xs' = xs.tail;
      g
    }