But my vote would be for { and } since *visually* they are much easier to
parse than begin and end and it is intuitively obvious as to what they do.
-steve
> From python-list-request@cwi.nl Thu Feb 24 12:37 PST 1994
> Date: Thu, 24 Feb 94 14:08:17 EST
> From: Chris Hoffmann <choffman@vicorp.com>
> To: python-list@cwi.nl
> Subject: multi-line expressions (was Python had a little lambda ...)
> Sender: python-list-request@cwi.nl
> Content-Type: text
> Content-Length: 3513
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>
>
> >> On Feb 23, 21:49, Bennett Todd wrote:
> >>
> >> >
> >> > Can this lambda support multi-line expressions? If not, is there any hope of
> >> > getting one that can?
> >> >
> >>
> >> The problem with multi-line lambda's in Python is:
> >> How do you embed one in a function using INDENT/DEDENT syntax ?
> >>
> >> ( And remember my complaints about not being able to do:
> >> "for x in seq : if f(x) : do_something" all on one line. )
> >>
> >> There would need to be a explicit printable symbol for the INDEDENT/DEDENT
> >> tokens. This might not be a bad idea, but I haven't thought it
> >> through.
>
>
> We've also identified the inability to create multi-line expressions
> as a weakness in Python syntax. I posted a message on 10 Dec 1993
> going in to a little more detail, but the key problem for us is that
> we don't want to force our users to adopt this style.
>
> For us programmers with fancy emacs' modes the INDENT/DEDENT system is
> fine. But for end-users, who may not be professional programmers
> and who may be entering text in a primitive text entry widget, having
> to get all their text to align properly will get stale fast.
>
> As I mentioned last time, when I show people Python they almost
> immediately complain about using indentation for nesting. I can only
> think of one or two people who didn't object to it. They may get to
> like it in time, but such a uniformly negative reaction may keep
> potential users from trying the language at all, slowing down its rate
> of acceptance.
>
> We've been looking for solutions to this problem. We'd really like to
> get a solution built in to the language rather than having to add
> something non-standard ourselves.
>
> Probably the best idea we've come up with is to add begin/end
> keywords. After a "begin" statement the lexer acts as if there had
> been a newline and an indentation to one more than the indentation of
> the line with the "begin". While inside a begin/end pair, the lexer
> considers all the lines to be at this same indentation level.
>
> Having "begin" simulate a newline allows the following to work:
>
> for x in seq : begin if f(x) : do_something; end
>
> Having the indentation be one more that that of the triggering line
> allows the following to work (which is clearly poor style, but should
> still be legal):
>
> if x : begin
> print x
> print x + 1
> end
>
> An occurance of a ":" terminated statement turns on the INDENT/DEDENT
> syntax until the indentation returns to the level of indentation of
> the statement that triggered it. This allows you to mix styles if you
> really want to.
>
> Reaching an "end" statement returns indentation to the level of the
> line that had the matching "begin" statement.
>
> Note that this is an addition to the current rules, not a replacement.
> We can still use the indentation syntax. The only problem for existing
> code is if the code uses "begin" or "end" as symbols. I'd prefer to
> use keywords instead of "{}" or other weird symbols, but maybe it's
> too late.
>
> I haven't had a chance to see how this affects the implementation of
> the interpreter or discover if there are hidden gotcha's in the
> syntax. My biggest concern so far is that I don't think you can do
> this entirely in the lexer, you need the parser to help out.
>
> I admit I'm not completely happy with this particular solution since
> it does muddy the current syntax. But we feel we have to address the
> problem somehow.
>
>
> Chris Hoffmann
>
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> Chris Hoffmann VI Corporation
> choffman@vicorp.com 47 Pleasant St. Northampton MA 01060
>