Haskell Cookbook

How to do it...

1. Create a new project log-parser with the simple Stack template:

        stack new log-parser simple

2. Open log-parser.cabal and add the library containers as a dependent library in the subsection build-depends of the section executable:

        executable log-parser
        hs-source-dirs:      src
        main-is:             Main.hs
        default-language:    Haskell2010
        build-depends:       base >= 4.7 && < 5
                     , containers

3. Open src/Main.hs and edit it. We will add log parsing and analysis here:

        module Main where

4. Import modules for file IO and the strict map:

        import System.IO
        import qualified Data.Map.Strict as M
        import System.Environment
        import Control.Monad

5. Read the file line by line:

 hLines :: Handle -> IO [String] hLines h = do isEOF <- hIsEOF h if isEOF then return [] ...