[R] "is" and the story of a typo

[Jim Lemon]

Hi all,
The gurus may pour scorn on me for not knowing this, but I happened to 
mistype "if" as "is" in the heat of debugging a function. As I scanned 
the debugged function with some satisfaction, I noticed the error. How 
could this have worked? I assume that "is" is a generic function that 
calls one of the is.* functions to evaluate whatever is passed. It 
appears that this particular typo causes "is" to work out and report the 
contents of its argument. Ho hum. As I did not test the FALSE result, I 
never would have noticed that it was not the conditional statement I 
expected until it evaluated something that should have been FALSE.

Jim