`functor', `args', `funargs'
----------------------------

functor(FUNC)
     :: FUNC ȡҤФ.
args(FUNC)
     :: FUNC ΰꥹȤФ.
funargs(FUNC)
     :: `cons(functor(FUNC),args(FUNC))' ֤.

RETURN
     `functor()' : 긵, `args()', `funargs()' : ꥹ
FUNC
     ȡɽ긵

   * ȡ˴ؤƤ, `vtype()' 򻲾.
   * ȡ FUNC ȡ, ꥹȤФ.
   * դ, ФȡҤͤ˻ĥץѿ `F' Ȥ 
     (`*F')(x) x ȤȡƤӽФޤȡϤǤ.

     [0] functor(sin(x));
     sin
     [0] args(sin(x));
     [x]
     [0] funargs(sin(3*cos(y)));
     [sin,3*cos(y)]
     [1] for (L=[sin,cos,tan];L!=[];L=cdr(L)) {A=car(L); print(eval((*A)(@pi/3)));}
     0.86602540349122136831
     0.5000000002
     1.7320508058


     `vtype'

