RGuide | Android新应用操作引导代码

Here's several style guides for writing R code 1, 2, and 3. They all deal with relatively "nice" examples that I'm able to follow. But let me paste some actual code I'm working with from R:

I know how to use <- and ->, and there are several writeups on the difference between equals assignment & arrow assignment, but I don't know when to prefer -> over <-.

It seems the community has coalesced around using <- for assignment.

Neither the google R style-guide, nor Hadley Wickam's tidyverse R style-guide even mention -> in the assignment section.

I'm curious about the design considerations that led the S/S-PLUS developers to put in the right arrow assign operator ->. In what setting(s) would using -> be considered more readable (or easier to type) versus <- or =?

I'm not familiar with any other language that allows the right-assignment semantics. What languages inspired R in this regard?

I'm looking for answers that cite books / early design documents / user manuals / archived mailing lists or other references to establish what the S author/designer's intent was in putting in the forward-arrow assignment operator.

I read the Google style guide for R. For "Assignment", they say:

Use <-, not =, for assignment.

GOOD:
x <- 5

BAD:
x = 5

Can you tell me what the difference is between these two methods of assignment, and why one is to be preferred over the other?