Re: [Caml-list] Bug or feature?

[Jesper Louis Andersen <jesper.louis.andersen@gmail.com>]

On Mon, Sep 12, 2011 at 14:56, Andrej Bauer <andrej.bauer@andrej.com> wrote:
> Would anyone wish to comment on this particular "feature" of toplevel?
>
>
>        Objective Caml version 3.12.1
>
> # let a = 12 ;; I CAN PUT ANY GARBAGE HERE AND IT GETS IGNORED
> val a : int = 12
>

It is a bug when you want to enter multiple statements, like in:

# let a = 12;; a + 30;;
val a : int = 12

But it is a feature when you want to use the toplevel as a way to
comment on what you are doing

# let prod x = List.fold_left (fun x y -> x*y) 1 x;; DEAR STUDENTS,
USE THIS DEFINITION TO DEFINE THE FACTORIAL FUNCTION

where the helpful feature of the top level makes it easier for the
student to just paste the whole line into the top level (except for
the # at the beginning, you can't have everything, can you?).

To conclude: It is a bug and a feature at the same time. Which is
quite peculiar, since it does not have mutual exclusivity in this case
(contrast to evaluation order where there is a right and a wrong one,
your mileage may vary - but you can't have both at the same time for
the same expression, though you can have both at different times for
the same expression :).

-- 
J.