Re: [Axiom-developer] Questions

[David MENTRE]

Stefan Dirnstorfer <address@hidden> writes:

> 2) The next one might just be a problem of recursive function
> definition. How else should it be done?
>
> (1) -> fac:= x+-> if x=0 then 1 else fac(x-1)
>   (10)
>      x
>    +->
>      if x= 0
>        then 1
>        else fac(x - 1)
>                                                       Type:
> AnonymousFunction
> (2) -> fac 1
>   >> System error:
>    Bind stack overflow.
>  protected-symbol-warn called with (NIL)

You should use following syntax:

(1) -> fac n == if n = 0 then 1 else n * fac(n-1)
                                                                   Type: Void
(2) -> fac 1
   Compiling function fac with type Integer -> Integer 
   Compiling function fac as a recurrence relation.

   (2)  1
                                                        Type: PositiveInteger
(3) -> fac 10

   (3)  3628800

In your above definition (fac:= x+-> if x=0 then 1 else fac(x-1)), I
think you define a _variable_ that _contains an _anonymous_
function. Apparently this function is unknown to Axiom when it looks for
the recursive call.

Yours,
d.
-- 
David MENTRE <address@hidden> -- http://www.nongnu.org/axiom/