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

[Stavros M. <mac...@al...>]

Use a=b to test structural equality.

equal(a,b) is for mathematical equality, and is unknown (not false) in the
absence of assertions (assume) about a and b.

On Sat, Jul 9, 2022, 16:57 Eduardo Ochs <edu...@gm...> wrote:

> 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
>
>
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