* Thomas Hartman wrote:
You contributed
#12:14 < Thunder> @pl s -> drop (length s - n) s #12:14 < lambdabot> drop =<< subtract n . length
But, on second thought, 1) I can't use this as a drop-in replacement for the non points free (right term?) version, and 2) I don't really understand it.
I did not contribute, but polluted the channel with my own test. In order to understand this construct you have to switch to the (-> a) Monad: drop =<< subtract n . length == do x <- subtract n . length drop x This construct consists of partially applied functions, i.e. functions waiting for an argument. If you apply an argument to the whole construct, it is applied to each line seperatly. So "drop =<< subtract n . length $ s" becomes: let x = subtract n . length $ s in drop x s == let x = length s - n in drop x s == drop (length s - n) s I did not expect this monadic approach from lambdabot and was somewhat surprised. I assumed an application of "liftM2 drop" instead.