# [ghc-steering-committee] #477: Unicode ellipsis, recommendation: reject?

Joachim Breitner mail at joachim-breitner.de
Tue Mar 1 15:21:33 UTC 2022

```Hi,

TIL! That’s indeed interesting research, and refutes my assumption that
.. was an ASCII-approximation of an ellipsis (aka \ldots in latex).

I thought for a moment that surely my typographic intuition is better
than Knuth’s, but … no, I didn’t.

I’ll bring this before the author and will see if he wants to pursue
the proposal anyways, retract it, or (maybe) suggest to use ‥ (U+2025
latter, given that I find essentially no prior art of using that.

Thanks for changing my mind,
Joachim

Am Dienstag, dem 01.03.2022 um 18:09 +0300 schrieb Vladislav Zavialov
(int-index):
> My -1 is firm. After some digging, I found out that the two dots are the intended notation, not just a shorthand for three dots. If you look at "Ronald L. Graham, Donald E. Knuth, and Oren Patashnik. Concrete Mathematics. Addison–Wesley, second edition, 1994”, you will find the following passage:
>
>     For our next problem let's consider a handy new notation, suggested by C. A. R. Hoare and Lyle Ramshaw, for intervals of the real line: [α .. β] denotes the set of real numbers x such that α ≤ x ≤ β. This set is called a closed interval because it contains both endpoints α and β. The interval containing neither endpoint, denoted by (α .. β), consists of all x such that α < x < β; this is called an open interval.
>
> The book is typeset beautifully, and I believe they could’ve used three dots if they wanted, but they used two. Since then, the Hoare-Ramshaw interval notation has been incorporated into various programming languages, including Pascal and Haskell.
>
> I have no idea why the proposal uses three dots, actually.
>
>
> > On 1 Mar 2022, at 17:42, Joachim Breitner <mail at joachim-breitner.de> wrote:
> >
> > Hi,
> >
> > it’s a worthwhile observation that we (somewhat oddly) use a two-dot
> > ellipsis in ASCII-Haskell, and Artem took this up on Github to ponder
> > if we should allow ASCII ... as well, but I am not convinced. I wrote
> > on the Github thread:
> >
> > > Hmm, I am not sure I agree that it's confusing. At least to me, from
> > > the start when I saw Haskell, the ascii .. meant what's \ldots in
> > > LaTeX, and what I tend to write as three close-to-each other dots on
> > > paper and is semantically an ellipsis, which in Unicode has a
> > > codepoint with that names that in most fonts looks like what you
> > > expect it to…
> > >
> > > So the .. is an ASCII cludge like all others (probably because ... is
> > > unnecessarily wide).
> > >
> > > The analogue is \ for λ - just because the left leg is missing we
> > > wouldn't use a unrelated look-alike like \ for the unicode variant,
> > > nor ask to be able to write ,\ in ASCII for a better approximation of
> > > the real letter.
> > >
> > > TL;DR: no need to change ASCII-Haskell, and let's use the
> > > semantically correct ellipsis symbol in Unicode-Haskell.
> >
> > is of course absolutely fine), I’d maybe just put this up for a vote?
> > It’s a mostly aesthetical, superficial change where voting may be more
> > efficient than long discussions.
> >
> > Cheers,
> > Joachim
> >
> > --
> > Joachim Breitner
> >  mail at joachim-breitner.de
> >  http://www.joachim-breitner.de/
> >
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