Get all sourced functions

In R, I am using source() to load some functions:

source("functions.R")

Is it possible to get the list of all functions defined in this file? As function names. (Maybe source() itself can somehow return it?).

PS: The last resort would be to call source() second time like local({ source(); }) and then do ls() inside and filter functions, but that's too complicated - is there easier and less clumsy solution?