Question

Based on other similar questions I found I figure my problem has to do with indentation, but I’ve messed with it a lot and still can’t figure it out.

addBook = do
    putStrLn "Enter the title of the Book"
    tit <- getLine
    putStrLn "Enter the author of "++tit
    aut <- getLine
    putStrLn "Enter the year "++tit++" was published"
    yr <- getLine

Answer 1

In your case it’s not indentation; you really have finished your function with something that is not an expression. yr <- getLine — what did you expect to happen to yr, or for that matter aut, after this? They’re just dangling, unused.

It may be clearer to show how this translates:

addBook = putStrLn "Enter the title of the Book" >>
          getLine >>= \tit ->
          putStrLn "Enter the author of "++ tit >>
          getLine >>= \aut ->
          putStrLn "Enter the year "++tit++" was published" >>
          getLine >>= \yr ->

So, what did you want to have following that last arrow?