Re: [Caml-list] Bug or feature?

[Philippe Wang <mail@philippewang.info>]

# let a = 32 ;; let b = 42 ;;
val a : int = 32
# b;;
Error: Unbound value b

Yeah... it's a little bit weird... not so great, actually. :-/

-- 
Philippe Wang
   mail@philippewang.info



On Mon, Sep 12, 2011 at 3:13 PM, Jesper Louis Andersen
<jesper.louis.andersen@gmail.com> wrote:
> 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.
>
>
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