R's unusual calling convention makes it very easy to write little DSLs and access program text at runtime. This I think makes for much more expressive APIs like

R's unusual calling convention makes it very easy to write little DSLs and access program text at runtime. This I think makes for much more expressive APIs like base R's formulas or dplyr's data manipulation facilities. In all other languages I know, formulas or data queries would need to be (quasi-)quoted or terms appearing in them would have to be declared to have a special type, spoiling the cleanness of the code