f(345,x=234,randomcharacters()+34-321==1)
[1] "f(345,x=234,randomcharacters()+34-321==1)"

g <- function(...) callstr(...)
g(345,x=234,randomcharacters()+34-321==1)
[1] "g(345,x=234,randomcharacters()+34-321==1)"

g <- function(...)deparse(sys.call())

g(345,x=234,randomcharacters()+34-321==1)
# [1] "g(345, x = 234, randomcharacters() + 34 - 321 == 1)"