Why does the list comprehension not generate a list of tuples?

Question

I try to make a macro for defining ctypes.Structure. The macro is listed as follows:

(defmacro struct [name fields]
`(defclass ~name [ctypes.Structure]
    [-fields- 
    ~(lfor i (range 0 (len fields) 2)
        (tuple [
        (str (get fields (+ i 1)))
        (get fields i)))]))

I think the lfor expression will generate a list of tuples, however, when I expand the macro using macroexpand, I found that the generated list is a list of lists, no tuple created. The result of macroexpand is given by:

=> (macroexpand '(struct Point [ctypes.c_int x ctypes.c_int y]))

HyExpression([
  HySymbol('defclass'),
  HySymbol('Point'),
  HyList([
     HySymbol('ctypes.Structure')]),
     HyList([
        HySymbol('-fields-'),
        HyList([
            HyList([
                HyString('x'),
                HySymbol('ctypes.c_int')]),
            HyList([
                HyString('y'),
                HySymbol('ctypes.c_int')])])])])

I am quite confused that the tuple in the lfor expression seems to not work at all.

Answer 1

Since I am a hylang newbie, I am not familiar with the mechanism of macro. After several attempts, finally I make it work properly, as follows:

(defmacro compound [typename name fields]
`(defclass ~name [~typename]
    [-fields- 
    ~(lfor i (range 0 (len fields) 2)
        `(, 
            ~(str (get fields (+ i 1)))
            ~(get fields i)))]))