Scheme - inconsistent highlighting

[johbra]

The highlighting of the Scheme function
(define add-point (lambda [p1 p2] (make-point (+ (point-x p1) (point-x p2)) (+ (point-y p1) (point-y p2)))))
using the following HTML document
`

<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.4.0/highlight.min.js"></script> <script charset="UTF-8" src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.4.0/languages/scheme.min.js"></script> <script>hljs.initHighlightingOnLoad();</script>

Code example

(define add-point
  (lambda [p1 p2]
    (make-point
      (+ (point-x p1) (point-x p2))
      (+ (point-y p1) (point-y p2)))))
        

` yields inconsistent highlighting: The fourth line of the function had to be highlighted exactly as the fifth line. But that's not the case.

[joshgoebel]

Strange indeed.

[joshgoebel]

May need a language champion for Scheme to sort this out. This type of syntax just give me a headache. :)

  var LAMBDA = {
    className:"lambda",
    begin: /lambda/,
    endsWithParent: true, returnBegin: true,
    contains: [
      NAME,
      {
        begin: /\(/, end: /\)/, endsParent: true,
        contains: [IDENT],
      }
    ]
  };

Our grammar expects a lambda to have a "name" and/or parens which include a list of "idents" (which we not highlight). This sound very similar to functionName(ident, ident) as found in other languages.

So it sees that first ( and then does nothing until it finds the first closing ), which snaps it back out of lambda and normal highlighting resumes.

[joshgoebel]

Is there another form where you pass the lamba arguments with () vs []? At a glance I see lots of code using () for args not [].

[johbra]

Maybe, the problem is that I'am using a variant of Scheme (Racket) where (x) can be replaced by [x] or {x} everywhere. So the expressions (lambda [x] (* x x)) and (lambda (x) (* x x)) are equivalent, for example.

[joshgoebel]

Is that a popular variant? Is that the only difference?

[johbra]

All I can say: Racket became popular by the well known text book How to design programs.

I am not sure but I don't know any further syntactical differences.

[joshgoebel]

What are () and {} used for in typical scheme?

[johbra]

All but simple expressions like numbers or symbols are enclosed in (). [] and {} aren't used at all.

[joshgoebel]

Think it would be helpful if we had another Scheme person to weigh in on this.

Isn't [] a list in Scheme?

[lechten]

I'm not a Scheme person, I use Emacs Lisp.

No, lists in Scheme are defined with round parentheses. Square brackets are allowed in some implementations, but they are reserved for future use, see there: http://community.schemewiki.org/?scheme-faq-language#H-yoyi82

They are still reserved in R7RS.