[m-users.] Coding style

[Richard O'Keefe]

There are good reasons that newspapers use narrow columns and many
journals and conferences use two-column format.
My Prolog style switched from 8-column indents to 4-column indents
years ago to improve readability.
I had a former colleague who was fond on full-monitor-width lines and
it was physically painful to read his code.
There are studies that say things like "reading text on a computer
screen is really exhausting" and "reading on a computer screen is
about 30% slower than reading printed text" and "longer lines require
increased line spacing" for readability" and "studies have recommended
that line length should not exceed about 70 characters per line" for
readability "both very short and very long lines slow down reading by
interrupting the normal pattern of eye movement."

With source code, we tend to do more *searching* than *reading
through*.  Long dense lines make searching hard.  I am not referring
to the kind of thing your text editor/IDE has for a 'search' command
unless you have a truly exceptional text editor that can express
structural patterns.  My former colleague believed he *needed*
extra-long lines because his variable names averaged about 20
characters long and his method names averaged about 30 characters
long.  He was half right: once you found a chunk of code you were in
little doubt about what it meant.  He was half wrong: it was the very
devil trying to distinguish between
current_input_stream_number_of_lines_read and
current_input_stream_number_of_lines_readable.

With source code, searching often involves more than one document.
When using R or Octave, I use the integrated help a *lot* so it
matters that the help and the file don't interfere with each other.
I'm often trying to look at a use of some name and the definition of
that name at the same time, and they are often in different files.  I
suggest that the best use of wide screens is to have several documents
side by side.

I must also point out that my most recent laptop has a 14-inch display
and that due to my spectacle prescription I'm a lot more comfortable
reading larger fonts.  The line width usable by someone with a 32-inch
monitor on their desk who is comfortable with 10 point type is a LOT
bigger than the line width usable by someone with a 14-inch laptop who
is more comfortable with 14-point type (who also has to keep a margin
clear for the Dock or its equivalent).  (Yes, I could buy a 32-inch
HDMI monitor that would plug into my laptop.  As it happens, I did.
But the point of a laptop is to be able to use it in places like the
local Chinese Garden, for which I have a season ticket, where I can't
plug the outboard monitor in.)

So when choosing your line length, please consider
 - people with 14-inch laptop screens
 - who need a larger font than you do
 - who are NOT familiar with your code and need to do a lot of searching
 - and really need to have multiple documents (use + definition, use
or definition + documentation)
   open at the same time.


On Thu, 22 Jan 2026 at 00:49, Julien Fischer <jfischer at opturion.com> wrote:
>
> Hi Ralph,
>
> On Wed, 21 Jan 2026 at 17:30, Ralph Becket <ralphbecket at outlook.com> wrote:
> >
> > Happy New Year!
>
> Happy new year to you too!
>
> > About twenty years back, when I left Mercury to start in mainstream commercial programming, monitors were a lot narrower.  There was a strong feeling then that 80 columns was the Right and Proper Line Length.  Nowadays, of course, monitors are much more generous.  While I reject uncontrolled line lengths, 80 columns seems painfully tight.  (I think the Linux developers moved away from this some years
> ago).  That said, when (back) in Rome, do as the Romans do.  So:
> what's the modern community position on this?
>
> In the Mercury project itself, it's still 80 columns (actually 79, due
> to diff adding an extra character).
>
> Outside of Mercury, I tend not to go beyond that too much (unless
> horribly verbose things like Java
> are involved).
>
> Julien.
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