I try to be economical when writing code; for example, I tend to use single quotes over double quotes for characters because it saves me one keystroke. One area where I don’t do that is when typing TRUE and FALSE (R accepts T and F as well), just because it is clearer to see in code and syntax highlighting kicks in. That’s why I was surprised to read Jason Morgan’s post in that it is possible to redefine T and F and get undesirable behavior.
Playing around it is quite easy to redefine other fundamental constants in R. For example:
> pi
[1] 3.141593
> pi <- 2
> pi*2
[1] 4
Ouch, dangerous! I tend to muck around with matrices quite a bit and, being a friend of parsimony, I often use capital letters to represent them. This would have eventually bitten me if I had used the abbreviated TRUE and FALSE. One can redefine even basic functions like ‘+’ and be pure evil; over the top, sure, but possible.