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2 points by malisper 3974 days ago | link | parent

I'm just wondering if the second rule is really such a good idea. If one wants to use indentation-sensitivity within parens, it is impossible. I'm not sure how often trying to write code like that would come up in practice, but I think the programmer should have the option in that case of whether indentation-sensitivity is actually being used (by using brackets or something else to make it clear).


2 points by akkartik 3974 days ago | link

I'm happy to rethink it if you can suggest an alternative way to suppress indent-sensitivity. I didn't have the second rule at the start, but was swayed by a discussion with the "readable s-expressions" project: https://www.mail-archive.com/readable-discuss@lists.sourcefo...; https://www.mail-archive.com/readable-discuss@lists.sourcefo.... It makes for an easily understood rule. What I had before took more than two sentences to explain: https://github.com/akkartik/wart/tree/7db61146b0#readme (search for 'suppress grouping')

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2 points by malisper 3973 days ago | link

Just have brackets (maybe curly braces) use indentation sensitivty.

  def (foo x y z)
    if [and
          x = 5
          y = 10
          z = 15]
      prn "success"
      prn "failed"
instead of

  def (foo x y z)
    if (and (x = 5) (y = 10) (z = 15))
      prn "success"
      prn "failed"
or

  def (foo x y z)
    if (and (x = 5)
            (y = 10)
            (z = 10))
      prn "success"
      prn "failed"

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1 point by akkartik 3973 days ago | link

But you have to have some way to suppress indent-sensitivity. How would you represent these?

  '(a reeeeeaaaally
    long line)

  def (foo a b c
           d e f)
    ..
Oh, are you suggesting suppressing indentation inside () but not inside []?

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2 points by malisper 3973 days ago | link

Yes, parens will not use indentation sensitivity, but brackets will. In that case the examples you gave would be valid code.

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1 point by akkartik 3973 days ago | link

Ok, interesting idea that I hadn't considered before.

As it happens, I've been watching a discussion about a different use for brackets: http://lambda-the-ultimate.org/node/4879. Lots of people (scheme, clojure, this liso guy) seem to have an idea about what to use brackets for, and it's not clear what the best use is for these precious punctuation characters.

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2 points by malisper 3973 days ago | link

I realized that we actually don't need to have a closing bracket to signal the end of the expression. We just need to implement something like the $ operator in haskell.

  def (foo a b c)
    if $ and
           a = 5
           b = 10
           c = 15
      prn "success"
      prn "failed"
There should be enough information based off of the indentation to tell how it should be parsed. $ should mean something along the lines of everything indented after the next symbol is a single expression.

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2 points by akkartik 3972 days ago | link

You'll like the old discussion on Bullet which had some similar ideas, including considering how to suppress paren-insertion inside such a special operator, etc.

http://web.archive.org/web/20120210015823/http://seertaak.po... (http://arclanguage.org/item?id=15769; http://www.reddit.com/r/programming/comments/pekx5/bullet_ad...)

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