Comment by chongli

I'm still a beginner at Idris, but here's my attempt at a "naive" wc:

    module Main

    wordCount : String -> IO ()
    wordCount file = let lineCount = length $ lines file
                         wordCount = length $ words file
                         charCount = length $ unpack file in
                         putStrLn $  "Lines: " ++ show lineCount
                                 ++ " words: " ++ show wordCount
                                 ++ " chars: " ++ show charCount

    main : IO ()
    main = do (_ :: filename :: []) <- getArgs  | _ => putStrLn "Usage: ./wc filename"
              (Right file) <- readFile filename | (Left err) => printLn err
              wordCount file

It counts lines, words, and characters. It reports errors such as an incorrect number of arguments as well as any error where the file cannot be read. Here are the stats it reports on its own source code:

    $ ./wc wc.idr
    Lines: 14 words: 86 chars: 581

Hope that helps.