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executable file 57 lines (44 sloc) 1.706 kb
#!/usr/bin/env runhaskell
import System.IO (stdin, stderr, stdout)
import Control.Applicative
import qualified Data.List as List
import qualified Data.Set as Set
import qualified Data.ByteString.Lazy as Bytes (hPutStr)
import qualified Data.ByteString.Lazy.Char8 as Bytes
import qualified Data.Char as Char
import System.Environment
import System.IO
import System.Exit
usage name = unlines
[ "USAGE: " ++ name ++ " n < some-lines"
, ""
, " Shuffles lines into groups of lines $n unique lines."
main = do
name <- getProgName
go name
go name = do
parsed <- digitize <$> getArgs
case parsed of
Left s -> fail s
Right i -> do
choices <- Set.fromList . no_empty . Bytes.lines <$> b_in
if Set.size choices < i
then fail "Not enough lines to choose from."
else do
(Bytes.hPutStr stdout . Bytes.unlines
. (Bytes.unlines . take i <$>)
. List.permutations
. Set.toList) choices
no_empty = filter (not . Bytes.all Char.isSpace)
fail s = do
hPutStrLn stderr s
hPutStrLn stderr ""
hPutStrLn stderr (usage name)
b_in = Bytes.hGetContents stdin
digitize [s] = case reads s of
[(i,"")] -> if i > 0 then Right i else Left "Non-positive."
_ -> Left "Argument error."
digitize _ = Left "Wrong number of args."
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