module General (foldlPair , openpair , openpair21 , openpair22 , wrppair , wrppair21 , wrppair22 , listRandomSelect) where

import System.Random

foldlPair :: (a -> b -> c -> a) -> a -> [(b , c)] -> a
foldlPair f y xs = foldl (wrppair22 f ) y xs

openpair ::  ((a , b) -> c) -> a -> b -> c
openpair f x y = f (x , y)

openpair22 :: (a -> (b , c) -> d) -> a -> b -> c -> d
openpair22 f x y z = f x (y , z)

openpair21 :: ((b , c) -> a -> d) -> b -> c -> a -> d
openpair21 f x y z = f (x , y) z

wrppair :: (a -> b -> c) -> (a , b) -> c
wrppair f (x , y) = f x y

wrppair21 :: (a -> b -> c -> d) -> (a , b) -> c -> d
wrppair21 f (x , y) z= f x y z

wrppair22 :: (a -> b -> c -> d) -> a -> (b , c) -> d
wrppair22 f z (x , y) = f z x y


listRandomSelect :: StdGen -> [a] -> (a , StdGen)
listRandomSelect rgen xs = let rand = randomR (0 , ((length xs) - 1)) rgen
			   in ((xs !! (fst rand)  ) , (snd rand))