[R] return inconsistency?

[Ben Bolker]

   Since R evaluates arguments 'greedily', it will evaluate the return() 
component (and return from the function) without even seeing the second 
component.

  This example might clarify things:

f <- function(x) { return(x)/stop("bad!") }
 > f(1)
[1] 1


Also possibly useful:

  lobstr::ast(return(OR^2+6*OR+1)/(OR*se^2))

█─`/`
├─█─return
│ └─█─`+`
│   ├─█─`+`
│   │ ├─█─`^`
│   │ │ ├─OR
│   │ │ └─2
│   │ └─█─`*`
│   │   ├─6
│   │   └─OR
│   └─1
└─█─`(`
   └─█─`*`
     ├─OR
     └─█─`^`
       ├─se
       └─2


On 2025-04-30 9:06 a.m., Duncan Murdoch wrote:
> `return` is a function.  I am away from my computer right now so I can't
> check, but I would expect you could create your own function named that.
> Other languages have `return` statements instead.
> 
> On Wed, Apr 30, 2025, 02:17 Ralf Goertz via R-help <r-help using r-project.org>
> wrote:
> 
>> I made a stupid error when programming a function. I used
>>
>>> return(OR^2+6*OR+1)/(OR*se^2)
>>
>> Being parenthesis blind it took me half an hour to find the reason for
>> the nonsensical results I got. I should have written
>>
>>> return((OR^2+6*OR+1)/(OR*se^2))
>>
>> Having said that why is the first variant (which returns the value of
>> the numerator only) not a syntax error? I would have expected R to
>> report something like
>>
>>> Error: unexpected '/' in "return(OR^2+6*OR+1)/"
>>
>> If this is not an error what is its purpose?
>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>> PLEASE do read the posting guide
>> https://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help using 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.

-- 
Dr. Benjamin Bolker
Professor, Mathematics & Statistics and Biology, McMaster University
Director, School of Computational Science and Engineering
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