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

Dave DeBarr ddebarr at uw.edu
Sun Nov 13 06:50:42 CET 2016

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?

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.


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

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