On Sun, Aug 22, 2010 at 4:33 PM, ivo welch <ivo.we...@gmail.com> wrote: > Dear R development Team: I really know very little, so you may ignore > this post. I have found that my students often make the mistake of > mixing up comparisons and assignments with negative numbers: > > if (x<-3) do_something; > > I parenthesize, but every once in a while, I forget and commit this > mistake, too. so, I would suggest that R simply warn about an > ambiguity. that is, it could suggest a space either between the < and > - , or after the <- . > > x< -3 ## means comparison already > x<- 3 ## means assignment already > but warn when > x<-3 ## ambiguity warning instead of assignment > x<-(whatever) ## ok > > just a suggestion... >
If you tell your students not to use '<-' for assignment, then they can't make this mistake, because = for assignment has additional restrictions on it: > x [1] 3 > if(x=3)print("yay") Error: unexpected '=' in "if(x=" Anyway, if students didn't make mistakes how will they learn about debugging? Barry ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel