[R] Question about expression parser for "return" statement

[Jeff Newmiller]

I find your response here inconsistent... either including `return` causes a "wasted" function call to occur (same result achieved slower) or the parser has an optimization in it to prevent the wasted function call (only behaviorally the same).

I carefully avoid using the return function in R. Both because using it before the end of a function usually makes the logic harder to follow and because I am under the impression that using it at the end of the function is a small but pointless waste of CPU cycles. That some people might be prone to writing a C-like use of "return;" which causes a function object to be returned only increases my aversion to using it. 
-- 
Sent from my phone. Please excuse my brevity.

On November 13, 2016 3:47:10 AM PST, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>On 13/11/2016 12:50 AM, Dave DeBarr wrote:
>> I've noticed that if I don't include parentheses around the intended
>return
>> value for the "return" statement, R will assume the first
>parenthetical
>> expression is the intended return value ... even if that
>parenthetical
>> expression is only part of a larger expression.
>>
>> Is this intentional?
>
>Yes, return is just a function call that has side effects.  As far as 
>the parser is concerned,
>
>return ((1/sqrt(2*pi*Variance))*exp(-(1/2)*((x - Mean)^2)/Variance))
>
>is basically the same as
>
>f((1/sqrt(2*pi*Variance))*exp(-(1/2)*((x - Mean)^2)/Variance))
>
>Duncan Murdoch
>
>>
>> I'm guessing it is intentional; but since there is no warning about
>> ignoring the rest of the expression, it could lead to hard-to-find
>bugs.
>>
>> Thanks,
>> Dave
>>
>> Here's an example ...
>>
>> dnorm(2, 0, 1)
>> normalDensityFunction = function(x, Mean, Variance) {
>>     # no parentheses surrounding the entire "return" value
>>     return (1/sqrt(2*pi*Variance))*exp(-(1/2)*((x -
>Mean)^2)/Variance)
>> }
>> normalDensityFunction(2, 0, 1)    # incorrect answer
>> normalDensityFunction = function(x, Mean, Variance) {
>>     # parentheses surrounding the entire "return" value
>>     return ((1/sqrt(2*pi*Variance))*exp(-(1/2)*((x -
>Mean)^2)/Variance))
>> }
>> normalDensityFunction(2, 0, 1)    # correct answer
>>
>> 	[[alternative HTML version deleted]]
>>
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>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>and provide commented, minimal, self-contained, reproducible code.