Re: Ignoring a list.

[Christopher Fry <cfry@OZ.AI.MIT.EDU>]

	    From: Gregor.pa@Xerox.COM
	    Subject: Re: Ignoring a list.
	
	    This seems like an environment issue to me, and not one that the
	    language needs to take a stand on.  After all:
	
	    - A particular environment might have some really nice way of
	    implementing and supporting this feature.  It could gray the form out,
	    or turn it blue or something. In that environment the "standard" way of
	    implementing it might not be useful or it might be difficult to provide
	    really nice environment support for it.
    ----------
    A particular environment might have a really nice way of supporting
    comments, say by displaying them in italics or boxes.  Therefore the
    standard shouldn't provide a standard way of indicating comments...
    ----------
Such a fancy environment could manage to hide a char sequence like #; 
	    - There is no significant need for a "standard" way to do this because
	    the only time a user really needs to comment out random forms (in a
	    hurry) is when they are debugging.
I spend most of my time debugging.
             If you are debugging then you
	    already have to learn enough about the environment that knowing how to
	    comment out a form does not seem like such a burden.
Yeah, but lets make it as easy as we can. 

    This isn't really a major issue, but the ability to comment out a
    form by marking the beginning of it seems like a very useful ability
    to have.  Marking both ends is (a) a pain in the ass, even if it does
    take only two keystrokes to get to the end of the form and (b) much
    more prone to the "oops, i took out the front one but not the back one"
    variety of error.
I agree. Here's the proposals for commenting out a form via prefix syntax that
I've seen so far:
#!        currently reserved for users
#-T       where T would be a feature of every implementation
#+IGNORE  Where IGNORE could not be a feature in any lisp implementation
#;        possible conflict with the syntax for comment to end of line
#+(or)    clever but not immediately obvious
#-(and)   clever but not immediately obvious

Most # letter combinations are presently undefined and not reserved for 
the user. Unfortunately, #c is used for complex numbers.
Maybe the next best is #d   {"Don't use"  or  "semantically Delete from program"}
There are about 10 other oddball chars that are not defined or reserved for
# reader macros. They are:
" $ % & > @ ^ _ ` ~

Out of these, I guess I'd favor #% but I have no strong preference.
#; is easy to remember for those of us already use to the semicolon comment.
How much editor or whatever code is out there that would have to be
modified?