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

I know it's an old post ... but it may be useful ...

in a pure "functional" way ...

greeting :: Maybe String -> String -> String
greeting Nothing name  = "Hello" ++ ", " ++ name
greeting (Just title) name  = "Hello" ++ ", " ++ title ++ " " ++ name ++ "!" 

how to call : 
-- greeting Nothing "John"
-- greeting Nothing "Charlotte"
-- greeting (Just "Mr.") "John"
-- greeting (Just "Miss.") "Charlotte"