T and TRUE / F and FALSE

[lorenzwalthert]

The Introduction to R states in section 2.4 that you should not use the abbreviations T and F for TRUE and FALSE since T and F are just variables that are set to TRUE and FALSE by default but can be overwritten by the user.

The tidyverse style guide, does not explicitly discourage the use of T and F, but always uses TRUE and FALSE as the logical values.

As of 00f0d96, styler does not convert the values T and F to TRUE and FALSE. Since T and F might have been assigned other values than the default, such a conversion would be highly problematic.
On the other hand, currently, T and F are just left as is, without message to the user, which is probably also not the thing we would expect from styler.

To conclude, checking for the usage of T and F and return a warning might be a reasonable way to go, so the user can resolve the problem manually.

[lorenzwalthert]

As of v1.2.0, styler does not emit a warning and leaves this to https://github.com/jimhester/lintr.