how to get the ordinal number in list

[Robert Kern]

On 2014-08-11 03:04, Steven D'Aprano wrote:
> Rustom Mody wrote:
>
>> Its when we have variables that are assigned in multiple places that
>> we start seeing mathematical abominations like
>> x = x+1
>
> That's not a mathematical abomination. It's a perfectly reasonable
> mathematical equation, one with no solutions since the line f(x) = x and
> the line f(x) = x+1 are parallel.
>
> But what does this have to do with programming? Programming *is not*
> mathematics, and x = x+1 has a different meaning in programming than in
> mathematics. Perhaps it would help if we wrote it using mathematical
> notation? Using [x] for subscripts:
>
> x[n+1] = x[n] + 1
>
> we have a perfectly good mathematical recursive definition. All it needs is
> an initial value x[0] and we're good to go.

Or a different operator for assignment (to distinguish it more clearly from 
equality, which it isn't).

   x <- x + 1
   x := x + 1

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco