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April 11, 2011 23:35
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Selection Sort in Haskell the hard (but easier for me) way.
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-- Selection Sort in Haskell | |
-- | |
-- Cheating by using IORef for mutable variables since I don't know what I'm doing | |
-- with Haskell, although do have an inkling that the benefit of Haskell is that | |
-- all of below can be done in about three lines. | |
-- | |
-- Assumes integer input only. | |
import Data.IORef | |
import Data.List.Split -- cabal install split | |
-- http://hackage.haskell.org/packages/archive/split/0.1.2.3/doc/html/Data-List-Split.html#v%3asplitOn | |
-- I'm not even going to think about doing this myself. | |
-- Used to get a comma delimted string as a list | |
main = do | |
-- Set up 'variables' | |
putStr "Enter List to Sort:" | |
stringinput <- getLine | |
let listinput = splitOn "," stringinput -- Convert comma delimited string to list | |
let intinput = [ read x :: Int | x <- listinput] --Convert list of strings to list of Integers | |
--Need to specify type http://learnyouahaskell.com/types-and-typeclasses | |
unsortlistIO <- newIORef intinput | |
elementIO <- newIORef [] | |
sortlistIO <- newIORef [] | |
sort unsortlistIO elementIO sortlistIO | |
sort unsortlistIO' elementIO' sortlistIO' = do | |
unsortlist <- (readIORef unsortlistIO') | |
sortlist <- (readIORef sortlistIO') -- initialise, for all intents and purposes | |
--print unsortlist --debug | |
if ((length unsortlist) > 0) | |
then do -- Note to self: Must remember to ident these after if! | |
-- find smallest element(s) | |
unsortlist <- (readIORef unsortlistIO') | |
writeIORef elementIO' (filter (==(minimum unsortlist)) unsortlist) | |
element <- readIORef elementIO' | |
-- Add to sorted list | |
sortlist <- readIORef sortlistIO' | |
writeIORef sortlistIO' (sortlist++element) | |
-- remove from original list | |
writeIORef unsortlistIO' (filter (not.(==(minimum unsortlist))) unsortlist) | |
readIORef sortlistIO' | |
--print sortlist --debug | |
sort unsortlistIO' elementIO' sortlistIO' -- loop. Ha! | |
else return sortlist -- Note to self: must be careful about returning the right type of thing |
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