Christian Hoffmann on Tue, 07 May 2013 23:26:14 +0200

[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

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

Am 11.03.13 10:41, schrieb Andreas Enge:
On Sun, Mar 10, 2013 at 08:13:14AM +0000, 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).


Delimiting tokens by blank space (including newlines) is serving well in the programming language "R" (see 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 W. Hoffmann,
CH - 8915 Hausen am Albis, Switzerland
Rigiblickstrasse 15 b, Tel.+41-44-7640853,,