[plt-scheme] Literate scribbling question

From: Eli Barzilay (eli at barzilay.org)
Date: Thu May 21 11:40:14 EDT 2009

On May 21, Anthony Cowley wrote:
> >> >> I was experimenting with the scribble/lp language, and found the
> >> >> need for the @chunks rather frustrating as they take up horizontal
> >> >> space and introduce a required chunk label.
> >> >
> >> > IIRC, it should work with something like @chunk[foo
> >> >
> >> >  (blah blah)
> >> >
> >> > ] just fine, does that help?
> >>
> >> That's the way I started out doing it when typing it in, but it's not
> >> DrScheme's default indentation pattern (so cmd-i or just hitting tab
> >> gives something worse).
> >
> > Well, if *that's* the problem, then hacking the syntax is the wrong
> > answer...  Right now writing any scribble code with drscheme (not only
> > lp code) is not really convenient, and hacking some scribble mode
> > would be -- as Robby said -- very welcome.  (It might be difficult
> > though because of the mixture of text and scheme modes -- even an
> > Emacs mode would probably be difficult.)
> I know indentation can be addressed on the DrScheme side, and I did
> not mean to highlight indentation as a big issue. But no matter the
> indentation style,
> @chunk[(define (foo x)
> (+ 'not-sure-where-this-line-goes x))
> ]
> is going to look different from normal Scheme code. I think I'd prefer
> to pay the two line penalty and have,
> @chunk[
> (define ...
> ]

Why not what I suggesed earlier then -- some text @chunk[


] and some more text here?  The code looks perfectly normal.

> > If the label is what bothers you (I'm ignoring the indentation
> > issue as I said above), then it would probably be possible to make
> > `chunk' more convenient.  For example, it could guess a chunk name
> > based on the previous chunk, or it could be made "smart" in the
> > sense that if a label identifier is omitted *and* the first form
> > is (or expands to) a (define foo ...) form, then it will use
> > `<foo>' as the label.  But IMO each of these can come with a
> > penalty in the form of more confusing bugs, for example -- with
> > the first strategy you could get confused results when you move
> > some text + code to a different place and getting a different
> > implicit label, and with the second strategy I can see this:
> I'm not looking for any guesswork. If a label can't be easily obtained
> (i.e. we have a define form), then there is no label. In my opinion,
> for the everyday coding scenarios I'm think about, the hyperlinks
> generated from the labels are a "nice to have" thing, but not a deal
> breaker. If a label can't be automatically extracted, then the
> fallback is some explicit annotation, but I wouldn't want the
> impossibility of always automatically extracting a label to be a
> blocking issue. This process is for generating human-readable text, so
> I don't think quite the same rigor need be applied as in the case of a
> compiler.

Oh, I didn't mean "guess", it would probably be better to use
"infer".  But the other problems I've mentioned are still there.  In
any case, it looks like you don't really want an LP tool, but a
semi-LP tool like the Haskell thing.

> To be honest, this aspect of using chunks (where one provides a
> partial implementation that refers to the label of another chunk)
> didn't really click with me. I'm still not sure when I would really
> want to do this rather than the more common (I think) literate
> programming style of just switching the reader into text mode part
> way through a definition. I almost never break up a function
> definition in any case, as I see the desire to do so as a sign that
> the function is probably too long. Again, in my opinion, I don't
> think this use-case should be a blocking issue. I may be missing
> some significant obvious utility, however.

Yes, you are talking about semi-LP here.

> > Trust me -- these kinds of \(...) hacks are not going to go well.
> > I've tried more than a few.
> This, I can't argue with :) I hoped that it wouldn't be *too* nasty
> a hack since you've already got a reader that switches modes on a
> single character, and we, as a community, also have some experience
> at escaping single characters in general. The left-paren in plain
> text escaping would be the *only* character that needs escaping, too
> (I think). I'm not looking to throw up a jungle of special-cased
> characters.

Hacking wouldn't be the problem (I've had a similar hack in a previous
version of this syntax which still exists in the mztext
preprocessor).  It's the nature of this kind of quoting that will make
it either inconvenient (quote backslashes too) or asymmetrical
(leading to confusing special cases and limitations).

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

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