haskell bruteforce

.gitignore

brute
brute.hi
brute.o

README

http://stackoverflow.com/questions/11391377/bruteforce-with-lazy-evaluation-and-memory-consumption

brute.hs

import Data.Maybe

bruteforce :: (a -> Bool) -> [a] -> Maybe a
bruteforce f xs
  | null result = Nothing
  | otherwise = Just $ head result
  where
    result = mapMaybe bruteforce' xs
    -- test one instance
    bruteforce' x
      | f x = Just x
      | otherwise = Nothing

generatorString :: Int -> [String]
generatorString 0 = [""]
generatorString deep = concatMap (\x -> map (\ys -> (x:ys)) nextgen) ['a'..'z']
  where nextgen = generatorString (deep - 1)


main :: IO ()
main = do
  putStrLn $ fromJust $ bruteforce ((==) "zabcde") (generatorString 6)

Makefile

SHELL := bash


all: brute

brutenolimit: all
	./brute +RTS -s

brute800: all
	./brute +RTS -s -M800M

brute200: all
	./brute +RTS -s -M200M


brute: brute.hs
	ghc --make -O2 $< -o $@ -rtsopts

.PHONY: all clean brutenolimit brute200 brute800
clean:
	rm -rf brute{,.o,.hi}