Re: [Maxima-discuss] foo(a, 2, 4, 1, 3) -> bar(bar(bar(bar(a, 2), 4), 1), 3) ?

[Eduardo O. <edu...@gm...>]

Hi,

I need a little more help...
This works nicely:

  foo1 : lambda([a, b], 10*a + b);
  xreduce(foo1, [2, 3, 4, 5]);
  xreduce(foo1, [2, 3, 4, 5], 9);
  foo(a, [b]) := xreduce(foo1, b, a);
  foo(9, 2, 3, 4, 5);

It yields:

  (%i1) foo1 : lambda([a, b], 10*a + b);
  (%o1)                      lambda([a, b], 10 a + b)
  (%i2) xreduce(foo1, [2, 3, 4, 5]);
  (%o2)                                2345
  (%i3) xreduce(foo1, [2, 3, 4, 5], 9);
  (%o3)                                92345
  (%i4) foo(a, [b]) := xreduce(foo1, b, a);
  (%o4)                 foo(a, [b]) := xreduce(foo1, b, a)
  (%i5) foo(9, 2, 3, 4, 5);
  (%o5)                                92345

Then I tried to replace foo1 by this:

  foo1 : lambda([o, action],
    if     equal(action, op)   then op(o)
    elseif equal(action, args) then args(o)
    else   args(o)[action]);

I was expecting to get this:

  foo(a+b*c, op)     ->         op(a+b*c)
  foo(a+b*c, args)   ->       args(a+b*c)
  foo(a+b*c, 2)      ->       args(a+b*c)[2]
  foo(a+b*c, 2, 1)   ->  args(args(a+b*c)[2])[1]

but my foo1 is broken - both foo(a+b*c, op) and foo1(a+b*c, op) return
"+", but foo1(a+b*c, args) and foo(a+b*c, 1) both return unevaluated
"if ..."s. How do I fix that? How do I force the evaluation of that
if?

  Thanks in advance!
    Eduardo Ochs
    http://angg.twu.net/eev-maxima.html