Initial data commit

Task/Evolutionary-algorithm/Haskell/evolutionary-algorithm-2.hs

@@ -0,0 +1,35 @@
+import System.Random
+import Data.List
+import Data.Ord
+import Data.Array
+import Control.Monad
+import Control.Arrow
+
+target = "METHINKS IT IS LIKE A WEASEL"
+mutateRate = 0.1
+popSize = 100
+printEvery = 10
+
+alphabet = listArray (0,26) (' ':['A'..'Z'])
+
+randomChar = (randomRIO (0,26) :: IO Int) >>= return . (alphabet !)
+
+origin = mapM createChar target
+    where createChar c = randomChar
+
+fitness = length . filter id . zipWith (==) target
+
+mutate = mapM mutateChar
+    where mutateChar c = do
+            r <- randomRIO (0.0,1.0) :: IO Double
+            if r < mutateRate then randomChar else return c
+
+converge n parent = do
+    if n`mod`printEvery == 0 then putStrLn fmtd else return ()
+    if target == parent
+        then putStrLn $ "\nFinal: " ++ fmtd
+        else mapM mutate (replicate (popSize-1) parent) >>=
+                converge (n+1) . fst . maximumBy (comparing snd) . map (id &&& fitness) . (parent:)
+    where fmtd = parent ++ ": " ++ show (fitness parent) ++ " (" ++ show n ++ ")"
+
+main = origin >>= converge 0