[Rd] detect ->

Adrian Dușa du@@@@dr|@n @end|ng |rom gm@||@com
Mon Apr 13 09:38:51 CEST 2020

I searched and tried for hours, to no avail although it looks simple.

(function(x) substitute(x))(A <- B)
#A <- B

(function(x) substitute(x))(A -> B)
# B <- A

In the first example, A occurs on the LHS, but in the second example A is somehow evaluated as if it occured on the RHS, despite my understanding that substitute() returns the unevaluated parse tree.

Is there any way, or is it even possible to detect the right hand assignment, to determine whether A occurs on the LHS?

Thanks in advance for any hint,

Adrian Dusa
University of Bucharest
Romanian Social Data Archive
Soseaua Panduri nr. 90-92
050663 Bucharest sector 5

More information about the R-devel mailing list