R's evaluation of arguments is lazy, so while not at the level of Haskell it feels like a lazy language to me. Try eg: f = function(x) { print('hello'); x }

R's evaluation of arguments is lazy, so while not at the level of Haskell it feels like a lazy language to me. Try eg: f = function(x) { print('hello'); x } f(print('world')) X is not evaluated in f until referenced. Indeed if you remove x from f, world is not printed.