Limber separators

[Herbert Valerio Riedel]

On 2016-05-31 at 15:42:14 +0200, Antonio Nikishaev wrote:

[...]

> Personally I don't need this extension per se since I don't care about one excess diff line.
> What I do care about however, is the horrendous style people invented to avoid “the diff problem”.
> As an example
>
> something = [ foo
>             , bar
>             , baz
>             ]

I'm not sure this style was invented to address the diff-problem, as it
actually doesn't solve the problem at all; it only shifts the problem
from the last entry to the first entry in the enumeration.

Moreover, why do you call this a "horrendous" style?

I actually see benefits for trailing separators as you avoid the
separator-alignment problem you'd have with trailing separators:

You either have to use a ragged alignment (and in this case the `,`s are
IMHO hard to see as they're visually attached to their entries; one can
add a whitespace before the `,` though)

 something = [
     one,
     thirteen,
     two,
     three
 ]

or if you align the `,`s on the same column to make move separators
visually out of the way, i.e.

 something = [
     one      ,
     thirteen ,
     two      ,
     three
 ]

you may run into a worse diff-problem, once you add an entry that is
longer and would require to realign all `,`s.

That's why I personally consider the "horrendous" style (and I even
catch myself sometimes using this in non-Haskell), i.e.

 something =
     [ one
     , thirteen
     , two
     , three
     ]

to have quit a few benefits in its own right. And while I don't *need*
this extension either, I've been tempted to implement such an extension
myself every now and then when I refactor code and fail to move the `,`s
around, resulting in an at least one additional edit-save-recompile
cycle.

> So I’d really like to see this extension, even if only to conquer the
> aforementioned style.

:-)

Well, I'd really like to see the grammar relaxed to allow for redundant
leading separators so I could finally use my personal ideal
diff-friendly style:

 something = [
     , one
     , thirteen
     , two
     , three
     ]