[Nmh-workers] Sequence Notation Torture.

[Ralph Corderoy]

Hi Ken,
> > http://lists.nongnu.org/archive/html/nmh-workers/2017-09/msg00014.html
...
> Secondly ... that message is kind of dense.

I think you mean `high in signal'.  It was partially to try and document
the current state of play.

> ...the way certain sequences make things go backwards is kind of
> confusing

Well, it's not too bad, but it would be simpler to explain if they
didn't.  I think it's a waste that `-', no prefix, and `+' are all
employed, but none is equivalent to one of the other two, varyingly.

           cur  ....5....
       next:-3  ...456...
        next:3  .....678.  Same as +
       next:+3  .....678.
       prev:-3  .234.....
        prev:3  .234.....  Same as -
       prev:+3  ...456...

I'd deprecate `+' so it can be used for something more useful in future.

There's lots of other oddities in that email, but I got exhausted before
spelling them all out.  I think a simpler notation would keep a name,
reserved or otherwise, as exactly its messages, so `first' is only ever
one email, and then provide means to subset/slice, e.g. last 3 of `mid',
`escape' out of the sequence into the folder at large, and not have to
specify the quantity when it's open ended.  With zero-based offsets, not
one.

-- 
Cheers, Ralph.
https://plus.google.com/+RalphCorderoy