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Re: First impressions of the specification

This page is part of the web mail archives of SRFI 110 from before July 7th, 2015. The new archives for SRFI 110 contain all messages, not just those from before July 7th, 2015.

On Wed, Mar 27, 2013 at 9:00 PM, Mark H Weaver <mhw@xxxxxxxxxx> wrote:
>>> * I have doubts whether the addition of '!' as an indentation character
>>>   is worth the added complexity in the spec (which is far more complex
>>>   than I'd prefer, and I'm sure I'm not alone in feeling that way).
>>>   Python seems to do fine without such a character.  So do Makefiles.
>>>   If it's truly needed, then it presents authors with a dilemma about
>>>   whether or not to put them in all the code that they write.
>> ! is surprisingly useful.  Here's an example which is readable, but
>> difficult to modify if you need to add an else clause:
>> define (foo x)
>>   define something $ cond
>>                        (pred1? x) $ begin
>>                                       something that is
>>                                       very long
>>                                       spanning several lines
>>                                       and might
>>                                         end up
>>                                           with severe
>>                                             changes in indentation
>>                                       like this
>>                                       and so on
>>                                         so forth
>>                                         whatsover ...
>>                        (pred2? x) $ begin
>>                                       another long clause
>>                                       involving several
>>                                         more lines
>>                                       and which
>>                                         also ends
>>                                           in
>>                                             (severe)
>>                                           changes
>>                                             in indentation
>>                                               at the end
>>   quux something
> Hmm.  I see what you mean, but I'd expect python to have the same
> problem, and yet they seem to do fine without this.
> For that matter, a similar example using traditional S-expressions could
> demonstrate the difficulty in adding a new clause and getting things
> lined up properly.  Of course, as you say:
>> In s-expressions, it's safe to lose a space or two when you insert a
>> clause at the end of the cond - the parens (should) guide the parser
>> to the correct insertion.
> and that's true in theory, but in practice we almost never see
> incorrectly indented S-expr code, and that's because almost everyone who
> writes Lisp gets a lot of help from modern editors.
> And that leads to my next question: has anyone written a nice emacs mode
> to help edit sweet expressions?  I think that such a mode will be
> crucial for adoption.  I doubt that many Lisp hackers will be interested
> in trying to get things lined up by hand.  We've had better tools for
> decades, and have grown accustomed to those conveniences.  Almost none
> of us want to go back to the stone age, no matter how nice it looks.

None so far, sadly.  Both dwheeler and I are vim users, me much more
so than David.  I have no real idea how modes work in emacs at all,
and vim-isms are quite ingrained in my fingers by now (hjkl when I
meant to use arrow keys to scroll, for example).  ! is a boon to me,
particularly with vim's Ctrl-V block selector and "r" commands.

dwheeler occassionally uses emacs I think (?) so he might be more
capable of doing this.