Re: [Caml-list] Coding style: mixing tabs and spaces in indentation

[Hendrik Boom <hendrik@topoi.pooq.com>]

On Tue, Jan 05, 2016 at 10:12:24AM +0100, Sébastien Hinderer wrote:
> Dear all,
> 
> I am wondering whether there are some guidelines that have been proposed
> regarding the way OCaml code should be presented?
> 
> More specifically: am I correct that it is considered not such a good
> practise to mix tabs and spaces in code indentation? And if so, are
> there objective reasons for that?
> 
> It seems Emacs is configured to do that (mixing tabs and spaces) by
> default, can anybody confirm?

It used to be (I'm talking 1960's and 70's here) that the standard was 
for a tab to be  equivalent to eight spaces.

No problem mixing tabs and spaces then.

But when people started programming a lot in C instead of assembler, 
the problem arose.  The recommended style was to use tabs for 
indentation.  The result was functions with very short lines of actual 
code when control structure was significantly nested.  Of course the 
style gurus would say that you had to break functions up at that point 
and that this wasa a useful indication that your indentation was too 
deep.  But many thought differently about style and started to indent 
less aggressively, perhaps two, four or even three spaces for each 
indent.  And to make that easy, they would set tab stops accordingly.

The result was that if tabs and only tabs were used for indentation, it 
would format nicely whatever your tab stop settings, and if spaces and 
only sppaces were used, it would also format nicely.  But if they were 
mixed, you would get a total mess if the tab width in the display were 
diffferent for that used when coding.

-- hendrik