Re: PARI 2.6 syntax 2: [f(x)|x<-a,b(x)]

[Christian Hoffmann <c-w.hoffmann@sunrise.ch>]

Am 11.03.13 10:41, schrieb Andreas Enge:
> On Sun, Mar 10, 2013 at 08:13:14AM +0000, Bernadette.Perrin-Riou@math.u-psud.fr wrote:
> > A naive question. What about [ 1, 2;
> > 3,4] if it is sensible to space ?
> Normally, a lexical analysis as done for the C or Java languages, for
> instance, would split this into the 9 one-character tokens
>   [ 1 , 2 ; 3 , 4 ]
> White space is allowed between tokens, here between ; and 3. And the special
> characters [ , ; ] are easily recognised as tokens of their own. A number
> like 12 would be recognised as one token, whereas with a space in between,
> it would be two tokens 1 and 2.
>
> Unless I have overlooked something, the proposed change would only mean you
> are not allowed any more to have white-space inside numbers, variables and
> function names or keywords such as "for" (also function names, strictly
> speaking, I suppose).
>
> Andreas
Delimiting tokens by blank space (including newlines) is serving well in 
the programming language "R" (see r-project.org). There we have ' <- ' 
for assignment (not =) and '==' for comparison.

The problem of large constants spanning more than one line could be 
solved by '\' at the end.

As for backward compatibility, in R a warning is published well in 
advance for the case of 'deprecated', that is features that will be 
abolished in some major revision in the future.

Christian

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