I agree there is no reason they _need_ to be the same precedence, but I think SPECIALS are already have the proper precedence for both unary and binary calls. Namely higher than all the binary operators (except for `:`), but lower than the other unary operators. Even if we gave unary specials their own precedence I think it would end up in the same place.
`%l%` <- function(x) tail(x, n = 1) %l% 1:5 #> [1] 5 %l% -5:-10 #> [1] -10 On Thu, Mar 16, 2017 at 6:57 PM, William Dunlap <wdun...@tibco.com> wrote: > I am biased against introducing new syntax, but if one is > experimenting with it one should make sure the precedence feels right. > I think the unary and binary minus-sign operators have different > precedences so I see no a priori reason to make the unary and binary > %xxx% operators to be the same. > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > > On Thu, Mar 16, 2017 at 3:18 PM, Michael Lawrence > <lawrence.mich...@gene.com> wrote: >> I guess this would establish a separate "namespace" of symbolic prefix >> operators, %*% being an example in the infix case. So you could have stuff >> like %?%, but for non-symbolic (spelled out stuff like %foo%), it's hard to >> see the advantage vs. foo(x). >> >> Those examples you mention should probably be addressed (eventually) in the >> core language, and it looks like people are already able to experiment, so >> I'm not sure there's a significant impetus for this change. >> >> Michael >> >> >> On Thu, Mar 16, 2017 at 10:51 AM, Jim Hester <james.f.hes...@gmail.com> >> wrote: >> >>> I used the `function(x)` form to explicitly show the function was >>> being called with only one argument, clearly performance implications >>> are not relevant for these examples. >>> >>> I think of this mainly as a gap in the tooling we provide users and >>> package authors. R has native prefix `+1`, functional `f(1)` and infix >>> `1 + 1` operators, but we only provide a mechanism to create user >>> defined functional and infix operators. >>> >>> One could also argue that the user defined infix operators are also >>> ugly and could be replaced by `f(a, b)` calls as well; beauty is in >>> the eye of the beholder. >>> >>> The unquote example [1] shows one example where this gap in tooling >>> caused authors to co-opt existing unary exclamation operator, this >>> same gap is part of the reason the formula [2] and question mark [3] >>> operators have been used elsewhere in non standard contexts. >>> >>> If the language provided package authors with a native way to create >>> unary operators like it already does for the other operator types >>> these machinations would be unnecessary. >>> >>> [1]: https://github.com/hadley/rlang/blob/master/R/tidy-unquote.R#L17 >>> [2]: https://cran.r-project.org/package=ensurer >>> [3]: https://cran.r-project.org/package=types >>> >>> On Thu, Mar 16, 2017 at 1:04 PM, Gabriel Becker <gmbec...@ucdavis.edu> >>> wrote: >>> > Martin, >>> > >>> > Jim can speak directly to his motivations; I don't claim to be able to do >>> > so. That said, I suspect this is related to a conversation on twitter >>> about >>> > wanting an infix "unquote" operator in the context of the non-standard >>> > evaluation framework Hadley Wickham and Lionel Henry (and possibly >>> others) >>> > are working on. >>> > >>> > They're currently using !!! and !! for things related to this, but this >>> > effectively requires non-standard parsing, as ~!!x is interpreted as >>> > ~(`!!`(x)) rather than ~(!(!(x)) as the R parser understands it. Others >>> and >>> > I pointed out this was less than desirable, but if something like it was >>> > going to happen it would hopefully happen in the language specification, >>> > rather than in a package (and also hopefully not using !! specifically). >>> > >>> > Like you, I actually tend to prefer the functional form myself in most >>> > cases. There are functional forms that would work for the above case >>> (e.g., >>> > something like the .() that DBI uses), but that's probably off topic >>> here, >>> > and not a decision I'm directly related to anyway. >>> > >>> > Best, >>> > ~G >>> > >>> > >>> > >>> > On Thu, Mar 16, 2017 at 9:51 AM, Martin Maechler >>> > <maech...@stat.math.ethz.ch> wrote: >>> >> >>> >> >>>>> Jim Hester <james.f.hes...@gmail.com> >>> >> >>>>> on Thu, 16 Mar 2017 12:31:56 -0400 writes: >>> >> >>> >> > Gabe, >>> >> > The unary functions have the same precedence as normal SPECIALS >>> >> > (although the new unary forms take precedence over binary >>> SPECIALS). >>> >> > So they are lower precedence than unary + and -. Yes, both of your >>> >> > examples are valid with this patch, here are the results and >>> quoted >>> >> > forms to see the precedence. >>> >> >>> >> > `%chr%` <- function(x) as.character(x) >>> >> >>> >> [more efficient would be `%chr%` <- as.character] >>> >> >>> >> > `%identical%` <- function(x, y) identical(x, y) >>> >> > quote("100" %identical% %chr% 100) >>> >> > #> "100" %identical% (`%chr%`(100)) >>> >> >>> >> > "100" %identical% %chr% 100 >>> >> > #> [1] TRUE >>> >> >>> >> > `%num%` <- as.numeric >>> >> > quote(1 + - %num% "5") >>> >> > #> 1 + -(`%num%`("5")) >>> >> >>> >> > 1 + - %num% "5" >>> >> > #> [1] -4 >>> >> >>> >> > Jim >>> >> >>> >> I'm sorry to be a bit of a spoiler to "coolness", but >>> >> you may know that I like to applaud Norm Matloff for his book >>> >> title "The Art of R Programming", >>> >> because for me good code should also be beautiful to some extent. >>> >> >>> >> I really very much prefer >>> >> >>> >> f(x) >>> >> to %f% x >>> >> >>> >> and hence I really really really cannot see why anybody would prefer >>> >> the ugliness of >>> >> >>> >> 1 + - %num% "5" >>> >> to >>> >> 1 + -num("5") >>> >> >>> >> (after setting num <- as.numeric ) >>> >> >>> >> Martin >>> >> >>> >> >>> >> > On Thu, Mar 16, 2017 at 12:01 PM, Gabriel Becker >>> >> <gmbec...@ucdavis.edu> wrote: >>> >> >> Jim, >>> >> >> >>> >> >> This seems cool. Thanks for proposing it. To be concrete, he >>> >> user-defined >>> >> >> unary operations would be of the same precedence (or just >>> slightly >>> >> below?) >>> >> >> built-in unary ones? So >>> >> >> >>> >> >> "100" %identical% %chr% 100 >>> >> >> >>> >> >> would work and return TRUE under your patch? >>> >> >> >>> >> >> And with %num% <- as.numeric, then >>> >> >> >>> >> >> 1 + - %num% "5" >>> >> >> >>> >> >> would also be legal (though quite ugly imo) and work? >>> >> >> >>> >> >> Best, >>> >> >> ~G >>> >> >> >>> >> >> On Thu, Mar 16, 2017 at 7:24 AM, Jim Hester >>> >> <james.f.hes...@gmail.com> >>> >> >> wrote: >>> >> >>> >>> >> >>> R has long supported user defined binary (infix) functions, >>> >> defined >>> >> >>> with `%fun%`. A one line change [1] to R's grammar allows users >>> to >>> >> >>> define unary (prefix) functions in the same manner. >>> >> >>> >>> >> >>> `%chr%` <- function(x) as.character(x) >>> >> >>> `%identical%` <- function(x, y) identical(x, y) >>> >> >>> >>> >> >>> %chr% 100 >>> >> >>> #> [1] "100" >>> >> >>> >>> >> >>> %chr% 100 %identical% "100" >>> >> >>> #> [1] TRUE >>> >> >>> >>> >> >>> This seems a natural extension of the existing functionality and >>> >> >>> requires only a minor change to the grammar. If this change >>> seems >>> >> >>> acceptable I am happy to provide a complete patch with suitable >>> >> tests >>> >> >>> and documentation. >>> >> >>> >>> >> >>> [1]: >>> >> >>> Index: src/main/gram.y >>> >> >>> >>> >> =================================================================== >>> >> >>> --- src/main/gram.y (revision 72358) >>> >> >>> +++ src/main/gram.y (working copy) >>> >> >>> @@ -357,6 +357,7 @@ >>> >> >>> | '+' expr %prec UMINUS { $$ = xxunary($1,$2); >>> >> >>> setId( $$, @$); } >>> >> >>> | '!' expr %prec UNOT { $$ = xxunary($1,$2); >>> >> >>> setId( $$, @$); } >>> >> >>> | '~' expr %prec TILDE { $$ = xxunary($1,$2); >>> >> >>> setId( $$, @$); } >>> >> >>> + | SPECIAL expr { $$ = >>> >> xxunary($1,$2); >>> >> >>> setId( $$, @$); } >>> >> >>> | '?' expr { $$ = xxunary($1,$2); >>> >> >>> setId( $$, @$); } >>> >> >>> >>> >> >>> | expr ':' expr { $$ = >>> >> >>> xxbinary($2,$1,$3); setId( $$, @$); } >>> >> >>> >>> >> >>> ______________________________________________ >>> >> >>> R-devel@r-project.org mailing list >>> >> >>> https://stat.ethz.ch/mailman/listinfo/r-devel >>> >> >> >>> >> >> >>> >> >> >>> >> >> >>> >> >> -- >>> >> >> Gabriel Becker, PhD >>> >> >> Associate Scientist (Bioinformatics) >>> >> >> Genentech Research >>> >> >>> >> > ______________________________________________ >>> >> > R-devel@r-project.org mailing list >>> >> > https://stat.ethz.ch/mailman/listinfo/r-devel >>> > >>> > >>> > >>> > >>> > -- >>> > Gabriel Becker, PhD >>> > Associate Scientist (Bioinformatics) >>> > Genentech Research >>> >>> ______________________________________________ >>> R-devel@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-devel >>> >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel