I didn't actually make a Google alert for "monadic functional IO"; I was just using it as an example of an esoteric topic.Lokathor wrote:Oh gosh I wish I knew Haskell more, but every time I sit down to do something I end up getting lost and derailed.CatharzGodfoot wrote:...or "monadic functional IO"
As an aside_____________________
I've been teaching myself Haskell by going through SICP, my 1st year intro to Computer Science textbook. I think I'm finally starting to `get` it: I was reading PL's "How to Write No Rules" thread, and decided to make an Excel spreadsheet to calculate and visualize die probabilities. After about 10 minutes I gave up and wrote some (probably unnecessarily complex and ugly) Haskell functions instead.
Code: Select all
import Data.Function
import Data.List
add1dY y = concatMap (\x-> map (+x) [1..y])
addXdY y 0 xDy = xDy
addXdY y x xDy = addXdY y (x-1) (add1dY y xDy)
combineXdY y x = toHistogram $ addXdY y (x-1) [1..y]
sumFreqs = foldr ((+).snd) 0
pGreaterHist histogram i = ((/) `on` fromInteger.sumFreqs) greater histogram
where greater = dropWhile ((<= i).fst) histogram
pLessHist histogram i = ((/) `on` fromInteger.sumFreqs) less histogram
where less = takeWhile ((< i).fst) histogram
toHistogram [] = []
toHistogram lst =
toHistogram' (x,1) xs
where (x:xs) = sort lst
toHistogram' pair [] = [pair]
toHistogram' (x1,n) (x2:xs) =
if x1 == x2
then toHistogram' (x1,n+1) xs
else (x1,n) : (toHistogram' (x2,1) xs)
showHistogram :: [(Int, Int)] -> IO ()
showHistogram = foldr (\ (i,n) y -> (putStrLn ((reverse $ take n bars) ++ " " ++ (show i))) >> y) (return ())
where bars = "|"++(cycle "-")
