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 — Adrian Dusa University of Bucharest Romanian Social Data Archive Soseaua Panduri nr. 90-92 050663 Bucharest sector 5 Romania https://adriandusa.eu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel