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Date: Wed, 8 Feb 2012 17:30:08 +0100
From: oliver <oliver@first.in-berlin.de>
To: David House <dhouse@janestreet.com>
Cc: Gabriel Scherer <gabriel.scherer@gmail.com>,
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X-Scanned-By: MIMEDefang_at_IN-Berlin_e.V. on 192.109.42.8
Subject: Re: [Caml-list] syntactic detail

On Wed, Feb 08, 2012 at 02:50:55PM +0000, David House wrote:
> On 02/08/2012 02:39 PM, Gabriel Scherer wrote:
> >People. Please. Tell me you are *not* arguing over underscores in
> >numeric literals !
> 
> This is not totally academic. I have come across the exact bug I
> describe. It was painful.
[...]


Let me guess where the problem might be came from:

When i think of code that uses a value
  1_000_000
  and you want to change it to a value ten times higher,
  it should be  changed to
  10_000_000


Coming from notation that does NOT allow "_" in tzhe numbers,
it could be done by just adding one "0" at the end of the value:

  1000000
becomes
  10000000
         ^

with the "0" added at the end.

But also correct ("more correct" would be:

  1000000
becomes
  10000000
   ^

"0" added at the millions.

  "Just add one "0" at the end"

Is the edit-habit, which works fine.


But when allowing "_" inside numbers,
but people don't change the "wrong" editing behaviour,
then allowing the "_" at all means introducing a new kind
of possible errors.

This could be an argument to throw "_" at all,
because adding a "0" after the "1" instead of just
adding a "0" at the end is rarely used behaviour of editing,
and some people might call it "weird". ;-)

So this argument also could be used to disallow "_" at all.


But no, thats not what I want to argue for ;-)



OK, let's stop that discussion now.

If someone thinks the three-digit-distance-"_" is a feature that makes sense,
a feature wish could be added for OCaml. ;-)


Ciao,
  Oliver