Re: Programming language and IDE design

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From	Hans-Peter Diettrich <DrDiettrich1@aol.com>
Newsgroups	comp.compilers
Subject	Re: Programming language and IDE design
Date	Thu, 05 Dec 2013 03:35:43 +0100
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Martin Ward schrieb:

> The difference is even smaller than this:
>
>      DO 10 I = 42.45
>      DO 10 I = 42,45
>
> The first is an assignment of a floating point value to variable DO10I,
> the second is a loop with I as the loop variable.
>
> Fortran allows spaces in the middle of identifiers, so requiring
> spaces around keywords does not help (unless you *also*
> disallow spaces within identifiers).
>
> The fact that the two statements can be distinguished with an LL(k)
> parser does not necessarily mean that the language is easy to read.

How would a LL grammar look like, when the lexer returns multiple tokens
for an identifier, here "DO","10" and "I"? With a traditional lexer I'd
suspect that such a language is *context sensitive*, with something else
for "LL(k)".

DoDi
[I suppose the prepass to tell whether it's an assignment is LL(1).  You definitely
need to preprocess the statement to tell whether it's an assignment or something
else.  After that, the parsing is very easy. -John]

Thread

Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-11-16 15:55 +0000
  Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-11-16 19:48 +0100
  Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-18 19:02 -0500
    Re: Programming language and IDE design "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2013-11-19 15:36 +0000
    Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-19 12:41 -0500
      Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-19 20:18 +0000
        Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-21 21:22 +0000
    Re: Programming language and IDE design wclodius@earthlink.net (William Clodius) - 2013-11-22 18:27 -0700
    Re: Programming language and IDE design "robin" <robin51@dodo.com.au> - 2013-11-25 10:33 +1100
      Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-12-03 15:15 +0000
        Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-12-05 03:35 +0100
    Re: Programming language and IDE design hu47121@usenet.kitty.sub.org (Hannah) - 2014-03-02 00:03 +0000
      Re: LL vs LR, was Programming language and IDE design Ivan Godard <ivan@ootbcomp.com> - 2014-03-01 20:31 -0800
        Re: LL vs LR, was Programming language and IDE design Kaz Kylheku <kaz@kylheku.com> - 2014-03-02 18:41 +0000
      Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2014-03-02 12:21 -0500
  Re: Programming language and IDE design Jonathan Thornburg <jonathan@cobalt.astro.indiana.edu> - 2013-11-19 19:39 +0000

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