This is in one sense a persistent topic across many area of computer science. Doubling up of characters as in ** as an exponentiation operator is far from unique. It probably is still being used in other computer languages as the only way to exponentiate using symbols. Rolf is correct that it may not be needed and John is correct that it likely is used and removing it, even with warnings, will likely cause problems.
Given the small number of symbols available in earlier times, including for example that ASCII has fewer than EBCDIC and far fewer than versions of UNICODE, it was inevitable that programmers and language developers preferred short groupings of symbols that often included doublings. Consider how many complaints have been seed for == versus just = ( and note I have also seen === and of course others like :=). What about mistakes between using > versus >> or other doubles like && and ||. Languages can have autoincrement operators like ++ with a matching -- and so on.Plenty of mistakes in programs have been caused when you used the wrong one for the purpose and yet it compiled and ran. Of course, R does not have all of these. R does allow some monstrosities to be defined as functions so I can do something like: Result <- alpha `+-&==` beta Simply searching for adjacent uses of "**" may pick up perfectly legitimate places where it is used, including in comments. I note some languages have comments around blocks of code done by programmers that look like this: /************************ Comment ************************/ Yes, the extra asterisks are not needed but I have seen lots of code commented this way for multi-line comments. And, I note in a language like SCALA, symbols used are dynamic. I can write code like: Result = Alpha ****** Beta The above line only works if you have created a method called "******" so the code can be invisibly rewritten as: Result = Alpha.******(Beta) Obviously, if object Alpha has not defined or inherited such a method, it fails. This can be a very powerful way to program but obviously opens the door to all kinds of problems. But that is true for many ares such as what happens if you have a function called paste0 and another called pasteo and call the wrong one. -----Original Message----- From: R-help <r-help-boun...@r-project.org> On Behalf Of Sorkin, John Sent: Tuesday, August 26, 2025 12:24 PM To: Deepayan Sarkar <deepayan.sar...@gmail.com>; Rolf Turner <rolftur...@posteo.net> Cc: r-help@r-project.org Subject: Re: [R] The "**" exponentiation operator. Rolf et al., While removing the ** syntax may fell attractive, removing it will cause legacy program to abend. This is not what one wants from a programming language. It might be better to add code to the parser that produces a wanting message that the ** syntax is not optimal and should be replaced with ^, but which allow legacy programs to run, albeit with a warning message. This will allow old programs to keep running and will prevent Rolf's fumbling finger from fatal flaws. Your thoughts? John John David Sorkin M.D., Ph.D. Professor of Medicine, University of Maryland School of Medicine; Associate Director for Biostatistics and Informatics, Baltimore VA Medical Center Geriatrics Research, Education, and Clinical Center; PI Biostatistics and Informatics Core, University of Maryland School of Medicine Claude D. Pepper Older Americans Independence Center; Senior Statistician University of Maryland Center for Vascular Research; Division of Gerontology and Paliative Care, 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 Cell phone 443-418-5382 ________________________________________ From: R-help <r-help-boun...@r-project.org> on behalf of Deepayan Sarkar <deepayan.sar...@gmail.com> Sent: Tuesday, August 26, 2025 11:55 AM To: Rolf Turner Cc: r-help@r-project.org Subject: Re: [R] The "**" exponentiation operator. On Tue, 26 Aug 2025 at 11:06, Rolf Turner <rolftur...@posteo.net> wrote: > > > > On more than one occasion I have got myself into trouble by > fumble-fingering and typing "**" when I intended to type "*". > Unfortunately the expression produced is syntactically correct and the > consequent incorrect results were difficult (for me) to disentangle. > > I would be much happier if the "**" operator were simply not allowed, > and threw an error. It seems to me that the existence of the "**" > operator is an archaism, probably deriving from Fortran. > > The documentation, obtained from ?Arithmetic, says at one point: > > > ** is translated in the parser to ^, but this was undocumented for > > many years. It appears as an index entry in Becker et al. (1988), > > pointing to the help for Deprecated but is not actually mentioned on > > that page. Even though it had been deprecated in S for 20 years, it > > was still accepted in R in 2008. > > It seems still be accepted in R in 2025. > > Would there be any mileage in asking R Core to deprecate "**", or > better still make it defunct? Can there be any rational basis for > keeping "**" around? Not a rational basis perhaps, but when I teach R to our newbie students who all want to learn Python, I have fun pointing out that ** is the official way to exponentiate in Python, and ^ does something quite crazy. So keeping ** around in R might make it a tad bit more welcoming to Pythonistas. Best, -Deepayan > cheers, > > Rolf Turner > > -- > Honorary Research Fellow > Department of Statistics > University of Auckland > Stats. Dep't. (secretaries) phone: > +64-9-373-7599 ext. 89622 > Home phone: +64-9-480-4619 > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide https://www.r-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.r-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
