Re: [Haskell-beginners] Non-exhaustive patterns

18 Nov 2017


      My complete code:

notThe :: String -> Maybe String
notThe word
  | word == "the" = Nothing
  | otherwise     = Just word

replaceThe :: String -> String
replaceThe word = go $ words word
  where
    go []     = ""
    go (x:xs) =
          case (notThe x) of
            Just x  -> x ++ " " ++ go xs
            Nothing -> " a " ++ go xs

On Sat, Nov 18, 2017 at 9:48 AM, Brody Berg  wrote:
...
Made some changes to replaceThe to handle the possibility of empty list:
replaceThe :: String -> String
replaceThe word = go $ words word
   where
      go [] = “”
      go (x:xs) =
         case (notThe x) of
            Just x -> x ++ “ “ ++ go xs
            Nothing -> “ a “ ++ go xs
Typed this on a phone, sorry
On Sat, Nov 18, 2017 at 09:16 Jim  wrote:
...
Hey guys,
Thiis is my function below:
notThe :: String -> Maybe String
notThe word
       | word /= "the" = Just word
       | word == [] = Just []
       | otherwise = Nothing
replaceThe :: String -> String
replaceThe word = go (words word)
       where go (x:xs)
               | notThe x == Just [] = []
               | notThe x == Just word = word ++ go xs
               | notThe word == Nothing = " a " ++ go xs
...
replaceThe "what"
"what*** Exception: chap12.hs:(13,13)-(16,55): Non-exhaustive patterns
in function go
I thought I covered all the potential patterns in my replaceThe
function. I'm not sure what pattern I've missed, any thoughts?
Best regards,
Jim
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