On 17 Nov 2017, at 18:32, Thierry Goubier <thierry.goub...@gmail.com> wrote:
Le 17/11/2017 à 10:14, Nicolas Cellier a écrit :
2017-11-17 17:40 GMT+01:00 Gabriel Cotelli <g.cote...@gmail.com
<mailto:g.cote...@gmail.com>>:
I would really like to see % removed as a binary selector and
available to use in unary or keyword ones. The only implementor in a
Pharo 6 image is:
% aNumber
^ self \\ aNumber
+1, such alias has nothing to do in Kernel
So it's juts aliasing \\ , and % most widespread usage in the real
world is por percentages (the use in modular arithmetic is more a
programming thing that math notation I think).
And for allowing more Unicode code points for selector names I'm
totally in for Symbols, Arrows, Math Symbols, etc... We just need to
analyse the ones that makes sense as binary selectors, and the ones
allowed for unary and keyword ones. This will allow us to write
pretty cool DSLs.
Just my opinion.
This could also be the case for punctuation like ! and ?
The idea of Torsten is more generic, any combination of binary char could be
used.
From what I understand from https://en.wikipedia.org/wiki/LR_parser we would
just have to scan one more token ahead for deciding if unary or binary, and
could preserve our simple shift reduce steps...
The Smalltalk parsers being handwritten, there wouldn't be shift/reduces to
contend with, and, anyway, the lexer doesn't shift/reduce; it would simply
creates a token up to the next separator (that is goble up the next
space/cr/end of line dot/closing parenthesis/etc...)
So it seems doable for resolving the send.
Sort of. The parser difficulty would be this one:
anObject % print
Is this a binary selector with a print argument or two unary selectors?
Using the symbol table when you parse would solve it, but that is certainly not
context free...
More problematic would be the declaration of method, if we have both a unary +
and a binary +, we will need new syntax for marking the difference.
In most cases, distinguishing between unary + declaration and binary +
declaration would be doable:
+ whatever
is the start of a binary selector
+ ^ self
is the start (or the declaration of) an unary selector.
But writing
+ self
Can be interpreted as either unary plus doing self, or binary + method
definition...
Whether it's worth or not is another matter...
Well, one should probably try to implement the various parsers for that (extend
RB, extend the SmaCC Smalltalk parser, extend the Petit Parser) to see how much
complexity it would bring.
Coming up with strange interpretations one could do with that syntax can be
helpfull as well.
Regards,
Thierry
On Fri, Nov 17, 2017 at 6:32 AM, Torsten Bergmann <asta...@gmx.de
<mailto:asta...@gmx.de>> wrote:
Hi,
just something to think about: one thing I always liked about
Smalltalk is that it allows for nice DSL's. We have nice things
like a unit framework in Pharo, ...
In the most simple case one can easily implement own units just
by providing a unary messages:
1 m
1 second
1 px
1 EUR
One can easily implement an own Money class with a currency and
then do polymorphic tricks like
10 EUR + 20 EUR
But we can currently can not implement special unary selectors
(including special unary selectors with unicode) like:
100 %
20 $
40 €
12 ‰ (for promille)
Especially things like 20 % would be nice for layout issues or
other (Bloc comes to mind).
Maybe we should put that on the roadmap of Pharo because IMHO it
would be cool to support such things in the
future. Dont know how much effort it currently means on the
technical level but maybe others can comment.
Thx
T.
