S Koray Can wrote:
As a newbie... I agree that a newbie should be able to write this fairly early on:
main = do x <- getLine() putStrLn ("The answer is " ++ show(fib(read(x))))
I'd agree for some definition of 'early'. I'll elaborate: [snip]
The above code snippet contains typeclasses (show, read, monadic IO, lists), syntactic sugar (do, <-). When you say a 'newbie' should be able to write that early on, I'd interpret that as 'a newbie should be able to regurgitate this early on'
Well, I'm a newbie, and I wrote it. I have "enough" understanding to generate that code, even if I don't understand it all. This is what I know: * x is a string, fib wants an int, and "read" turns a string into a number. * "The answer is " is a string so you need ++. ++ expects a string, and "show" turns a number into a string. So, yes, I need *basic* knowledge of types (strings vs numbers) and the functions that convert from one to the other. But that's it. I don't need to know that "do" and "<-" are syntactics sugar, or what a monad is (heck, I don't know those things). I think that the following is suitable for chapter 1: --//-- main = do putStrLn "What is your name? " name <- getLine putStrLn("Hello " ++ name) --//-- You don't need to learn about monads, or classes or lists for this. Yes, not even lists ("Use ++ to catenate strings"). All you need to know is strings, and that "name <- getLine" gets a line from input and puts it in 'name'. I think that this is suitable for chapter 2: --//-- main = do putStrLn "Please type a word:" word <- getLine putStrLn("This word has " ++ (show( length word)) ++ " letters") --//-- Here you learn about numbers, and converting numbers to strings (show). And this is for chapter 3: --//-- main = do putStrLn "Please type a number:" number <- getLine putStrLn (number ++ "! = " ++ (show (fac read(number))) --//-- Here you learn about converting a string to number. At some point between chapters 1 and 3 you'd learn how to write 'fac' (I guess chapter 1). Cheers, Daniel. -- /\/`) http://oooauthors.org /\/_/ http://opendocumentfellowship.org /\/_/ \/_/ I am not over-weight, I am under-tall. /