It looks like your latest version works. This also works: *Temp> let replaceThe = unwords . map (\i -> if i=="the" then "a" else i) . words *Temp> replaceThe "is the bat" "is a bat" *Temp> On Sat, Nov 18, 2017 at 10:46 AM, Brody Berg wrote:

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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