Thursday, November 29, 2012

Re: Indenting Based on Unbalanced Paranthesis

Apologizes for the top posting,

No indenting exists for this previously, it's a language (currently unnamed) I'm writing as an experiment in functional programming and to learn to parse.


I can't think of any other markers really, the syntax for the language is pretty minimalistic, here's a quicksort implementation that has 95% of the language in it:

quicksort (ls) := 
    if (= (length ls) 1) 
        ls
        (let
            pivot = car ls,
            less  = filter (lambda(x) -> < x pivot) (cdr ls),
            more  = filter (lambda(x) -> >= x pivot) (cdr ls),
            in:
                append (quicksort less) (cons pivot (quicksort more)));

main := quicksort [1 2 3 5 18 4 1 4 1 4]

Since () are used to group function applications their extremely common. I was originally thinking a syntax similar to Scheme's or Common Lisp's might do it, but I'm confused how they manage it based on their indent files, I'm still pretty newbie-ish at this sort of vim stuff.
 


On Thu, Nov 29, 2012 at 6:08 PM, Benjamin R. Haskell <vim@benizi.com> wrote:
[Reversed the top-posting, per list preference]


On Thu, Nov 29, 2012 at 5:24 PM, Danny Gratzer wrote:

I am writing an indentation script for a simple language. The language is has very simple constructs and the indentation really only has 3 rules:

1. A comment has goes from a // until a newline, anything in a comment should be ignored.

2. If the line above contains a semi-colon, the indentation should be 0.

3. Otherwise, indent to 1 more than the most recent unbalanced ( and to 4 spaces if all paranthesis are balanced.

The last rule is kinda stumping me, does anyone have any advice?

Don't write the indent file if you don't have to. What language are you trying to indent?

Indenting gets slow if you have to scan the whole file.  Unless you're never dealing with at-all long files.  Is there anything other than semi-colons and parenthesis (im)balance that can be used for resetting indentation?



On Thu, Nov 29, 2012 at 5:27 PM, Danny Gratzer wrote:

Oh actually 1 more rule

4. If the line above matches "let:$", or "in:$" where $ is the end of
line, indent by 1 more than this line.

On Thu, 29 Nov 2012, Danny Gratzer wrote:

Excuse me, rule 3. should read:

3. Otherwise, indent to 1 more than the most recent unbalanced ( and to the
same level as the last line if all parenthesis are balanced and no other
rules apply.

It'd be helpful to see some samples of what you're trying to indent. Especially to see whether the scan all the way to the start of the file can be avoided.

--
Best,
Ben

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Danny Gratzer

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