-- Nested lists

type list {
  nil : list;
  cons : * -> list -> list;
}

function mklst(integer) : list {
  push 0;
  push arg[0];
  eq;
  br {
    true: {
      alloc nil;
      ret;
    };
    false: {
      push 1;
      push arg[0];
      sub;
      call mklst;
      push arg[0];
      alloc cons;
      ret;
    };
  };
}

function mklst2(integer) : list {
  push 0;
  push arg[0];
  eq;
  br {
    true: {
      alloc nil;
      ret;
    };
    false: {
      push 1;
      push arg[0];
      sub;
      call mklst2;
      push arg[0];
      call mklst;
      alloc cons;
      ret;
    };
  };
}

function append(list, list) : list {
  push arg[0];
  case list {
    nil: { pop; push arg[1]; ret; };
    cons: {
      pop;
      push arg[1];
      push arg[0].cons[1];
      call append;
      push arg[0].cons[0];
      alloc cons;
      ret;
    };
  };
}

function flatten(list) : list {
  push arg[0];
  case list {
    nil: ret;
    cons: {
      pop;
      push arg[0].cons[1];
      call flatten;
      push arg[0].cons[0];
      tcall append;
    };
  };
}

function main() {
  push 4;
  call mklst2;
  trace;
  call flatten;
  trace;
  pop;
  push void;
  ret;
}