The operator <- can be used anywhere whereas the operator = can only be used at top level. It will be more clearer when it’s used to set an argument value in function call.
You can also use one of the tidy_* functions in the formatR and it will automatically replace = with <-. Ex.
tidy_source(text = "x=1:5", arrow = TRUE)
## x <- 1:5
To fix the error of your syntax use prefix notation for assignment.
x <- 6
`<-`(x, 6) #same thing
y = 6 `=`(y, 6) #also the same thing
parser interprets x <- y <- 6 as
`<-`(x, `<-`(y, 6))
Our expectation is that x <- y = 6 would then be
`<-`(x, `=`(y, 6))
but actually it will result as
`=`(`<-`(x, y), 6)
This is happening because = is lower precedence than <-
Hope this helps.