Question

I try to use CmdArgs to extract an integer from the command line arguments:
./prg –byte=512

The below code does not compile and the compiler says Couldn't match expected type `Int' with actual type `Strlen -> Int'. Now, I thought that I had deemed byte to be an integer? Isn’t it?

{-# LANGUAGE DeriveDataTypeable #-}
import System.Console.CmdArgs

data Strlen = Strlen {byte :: Int} deriving (Data, Typeable)

strlen = cmdArgsMode $ Strlen {byte = def} 

main = do
        n <- cmdArgsRun strlen 
        let datastring = take byte $ randomRs ('a','Z') (mkStdGen 3)

Answer 1

To select the byte field from n you need to say byte n. So

let datastring = take (byte n) $ randomRs ('a','Z') (mkStdGen 3)