How to chain the use of maybe argument in haskell?

Question

I\'m trying to build a string from optional arguments. For example to generate a greeting string from a title and a name This is trivial in a imperative language and would l

Answer 1

You could avoid using a Maybe for the title and do:

greeting :: Bool-> Maybe String -> String
greeting title name = "Hello" ++ title' ++ (maybe "" id name)
  where title' = if title then "Mr" else ""

If you have a number of Maybes you could use mconcat since String is a monoid:

import Data.Monoid
import Data.Maybe

greeting :: [Maybe String] -> String
greeting l = fromJust $ mconcat ((Just "Hello"):l)