syntax of commenting (was: Re: [plt-scheme] Student parsing problem)

From: John Clements (clements at
Date: Wed Jun 3 16:08:54 EDT 2009

On Jun 3, 2009, at 12:04 PM, Eli Barzilay wrote:

> On Jun  3, John Clements wrote:
>> I think you're misunderstanding me; what I'm pointing out is that
>> for a COMMENT form to work correctly, it would have to be a reader
>> form-- like #; , and like #| |#--and not a macro.  It just happens
>> to be a reader form that our textual editors can already handle
>> conveniently.
> This only gets you deeper into the quicksand.  What about:

I think I'm already over my head in quicksand, so there's no point in  
stopping now.

>  (parameterize ([read-case-sensitive #f])
>    (read (open-input-string "(comment ...)")))
> or any of these:
>  [COMMENT ...]
>  (\COMMENT ...)
>  #(COMMENT ...)
>  (COMMENT...)   for example (COMMENTARY ...)
> And I didn't even begin to talk about confusions like
>> (list-ref '(COMMENT 3) 0)
>  list-ref: expects 2 arguments, given 1: 0

I suspect that most of these have naive solutions at the reader level  
that work pretty well


I realize that there's really no need to add anything to the language,  
because you can already have what I'm proposing (except for the  
convenient swap-out) by using



... and in fact that's what I already do.

So, I guess my observation boils down to this:  I think that  
forbidding sequenced #;'s would not significantly impact the  
expressiveness of the editor experience.

It _is_ an argument for the more widespread use of C-c C-e, though. :)

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