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Today's Topics:
1. Non-exhaustive patterns (Jim)
2. Re: Non-exhaustive patterns (Brody Berg)
3. Re: Non-exhaustive patterns (Brody Berg)
4. Re: Non-exhaustive patterns (Jeffrey Brown)
----------------------------------------------------------------------
Message: 1
Date: Sat, 18 Nov 2017 13:15:51 -0400
From: Jim <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [Haskell-beginners] Non-exhaustive patterns
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8; format=flowed
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
------------------------------
Message: 2
Date: Sat, 18 Nov 2017 17:48:11 +0000
From: Brody Berg <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Non-exhaustive patterns
Message-ID:
<CAGAyAWOe2mep6376ToqWf4uy=tukb3lfdbrzflstvzxxuwe...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
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 <[email protected]> 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
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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Message: 3
Date: Sat, 18 Nov 2017 10:46:04 -0800
From: Brody Berg <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Non-exhaustive patterns
Message-ID:
<cagayawnvgcfvxk6yioq4vxndltrywcq35ot9xo+ihza-a0j...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
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 <[email protected]> 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 <[email protected]> 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
>>
>> _______________________________________________
>> Beginners mailing list
>> [email protected]
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>>
>
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Message: 4
Date: Sat, 18 Nov 2017 11:15:23 -0800
From: Jeffrey Brown <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Non-exhaustive patterns
Message-ID:
<CAEc4Ma2R_2qFnV4uGnN=qNo++ctMS=vsl8dupxbdmqufgu5...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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
>>>
>>> _______________________________________________
>>> Beginners mailing list
>>> [email protected]
>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>>>
>>
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
--
Jeff Brown | Jeffrey Benjamin Brown
Website <https://msu.edu/~brown202/> | Facebook
<https://www.facebook.com/mejeff.younotjeff> | LinkedIn
<https://www.linkedin.com/in/jeffreybenjaminbrown>(spammy, so I often miss
messages here) | Github <https://github.com/jeffreybenjaminbrown>
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