Re: Case statement and Integers.

[tmoran@acm.org]

>       case numbers(j) is
>               when numbers(j) < pivot => swap(left_swap, right_swap);
>               when numbers(j) > pivot => swap(right_swap, left_swap);
>               when numbers(j) = pivot => null;
>               when others => null;

  The items after the "when" must be constant values of "numbers(j)".
This code has dynamic boolean expressions.  "case" is not just another
syntax for "if then".  When the compiler sees a "case" statement it
should, at least conceptually if not in implementation, be able to create
a jump table indexed by the value of "numbers(j)".  It clearly can't do
that here.
If you had a comparison function
  type Compare_Results is (LT, EQ, GT);
  function Compare(Left, Right : Numbers_Type) return Compare_Results;
then you could say
  case Compare(numbers(j), pivot) is
    when LT =>
    when GT =>
    when EQ =>
  end case;
because the compiler could create a three-entry jump table.

> Using an if..else statement wouldn't be original.
  Bicycling to Hawaii is original - but it won't work either.  In
Software Engineering, the point is to make something that works, not
necessarily something original.  In fact, since you will abandon most of
your code to your maintenance successors (one hopes you move on to new
things!), and originality will just confuse them, originality itself is a
downright *negative* aspect of code, to be used only when the negative is
outweighed by the positive benefits of the novel technique.