Re: finite field

[Karim BELABAS <Karim.Belabas@math.u-psud.fr>]

[Bill:]
> The way function definition are defined in the GP grammar are *bad*
> I spend hours to explain my Yacc parser how to handle that.
> 
> This syntax is context-dependent and use "\n" as a terminator...

it's even worse than that actually (examples below).

> If you start like this
> 
> f(x)=g(a)=sin(a);<code>
> 
> There is no way to add code to f after the definition of g...
> You must use something like
> 
> f(x)=if(1,g(a)=a+x);g(3)

Not necessarily, I myself use 

  f(x) = (g(a)=sin(a));<more code for f>

all the time, mostly to emulate pointer to functions, and alternate between
different sets of routines. In fact, I use the marginally cleaner approach

  switch(flag) = {
    if (flag,
      (f1() = ...);   \\ or alias(f1, other_routine1), if I need efficiency
      (f2() = ...);
    ,
      (f1() = ...);   \\ or alias(f1, other_routine2)
      (f2() = ...);
    )
  }

> Beside f and g have separated variable scope :
> ? f(5)
> %3 = 8
> ? g(0)
> %4 = x
> ?

Indeed. I would expect it to work that way. How would you react if

 a = 1
 f(x) = x + a

defined f(x) as x + 1 ?  It's the same situation, unnested to global scope.

> I don't if there is valuable use of nested definition,
         ^ know ?

There definitely is.

> I thing that nested definition should at least trigger a warning,

your compiler can do that.

> and even perhaps be forbidden.

No. Because, as you point it,
> On the opposite, add the possibility to affect function to variable

Cheers,

      Karim.
-- 
Karim Belabas                    email: Karim.Belabas@math.u-psud.fr
Dep. de Mathematiques, Bat. 425
Universite Paris-Sud             Tel: (00 33) 1 69 15 57 48
F-91405 Orsay (France)           Fax: (00 33) 1 69 15 60 19
--
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