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Today's Topics:
1. Re: error: Not in scope: data constructor `BinTree' (Kak Dod)
----------------------------------------------------------------------
Message: 1
Date: Sat, 14 Apr 2012 03:28:25 +0800 (SGT)
From: Kak Dod <[email protected]>
Subject: Re: [Haskell-beginners] error: Not in scope: data constructor
`BinTree'
To: Kyle Murphy <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
I wants to create things that way only,
yes, later I may add another constructor like "Leaf a"?
sorry for the confusion in my question .
now i comes to know that all I wants to know was syntax of how to write "Node
BinTree a" instead of? "Node a BinTree a" and there was many horrorful error
messages like: Expected kind `?', but `BinTree' has kind `k0 -> *'
that why i have panic that time
i was not seen that error earlier
thank you for answer
________________________________
From: Kyle Murphy <[email protected]>
To: Kak Dod <[email protected]>
Cc: Tom Murphy <[email protected]>; "[email protected]"
<[email protected]>
Sent: Friday, 13 April 2012 6:32 PM
Subject: Re: [Haskell-beginners] error: Not in scope: data constructor `BinTree'
If you don't include "Node a" then there isn't any point in having the a
parameter on BinTree as it's never used unless you add another constructor that
uses it. I based the modification on the usage in your example where you're
trying to store a value of 3. Without that parameter the code becomes:
b1 = Node EmptyBinTree EmptyBinTree
I haven't tried it, but that will also likely complain it can't deduce "a" from
the usage.
-R. Kyle Murphy
Sent from my phone.
On Apr 13, 2012 1:03 PM, "Kak Dod" <[email protected]> wrote:
Thanks Tom. this is what i wanted
>I do not want "Node a" there, I wants only Node and Tom's solution works.
>Thanks to all .
>
>
>
>________________________________
> From: Tom Murphy <[email protected]>
>To: Kak Dod <[email protected]>
>Cc: Kyle Murphy <[email protected]>; "[email protected]"
><[email protected]>
>Sent: Friday, 13 April 2012 4:53 PM
>Subject: Re: [Haskell-beginners] error: Not in scope: data constructor
>`BinTree'
>
>"(BinTree a)" needs to be in parentheses to pattern-match properly.
>
>data BinTree a = Node (BinTree a) (BinTree) a | EmptyBinTree
>? deriving Show
>
>On 4/13/12, Kak Dod <[email protected]> wrote:
>> Thank you but
>>
>> if I change the code like this:
>>
>> data BinTree a = Node BinTree a BinTree a | EmptyBinTree deriving Show
>>
>> b1 = Node 3 EmptyBinTreeEmptyBinTree
>>
>> Then I am get this error:
>>
>> bintree.hs:1:23:
>> ??? `BinTree' is not applied to enough type arguments
>> ??? Expected kind `?', but `BinTree' has kind `k0 -> *'
>>
??? In the type `BinTree'
>> ??? In the definition of data constructor `Node'
>> ??? In the data type declaration for `BinTree'
>> Failed, modules loaded: none.
>>
>>
>>
>>
>> ________________________________
>>? From: Kyle Murphy <[email protected]>
>> To: Kak Dod <[email protected]>
>> Cc: "[email protected]" <[email protected]>
>> Sent: Friday, 13 April 2012 4:38 PM
>> Subject: Re: [Haskell-beginners] error: Not in scope: data constructor
>> `BinTree'
>>
>>
>> Your constructor
is called Node, not BinTree.
>> data BinTree a = Node a (BinTree a) (BinTree a) | EmptyNode
>> b1 = Node 3 EmptyNode EmptyNode
>> -R. Kyle Murphy
>> Sent from my phone.
>> On Apr 13, 2012 12:24 PM, "Kak Dod" <[email protected]> wrote:
>>
>> if i compile the following code I get "bintree.hs:3:13: Not in scope: data
>> constructor `BinTree'"
>>>
>>>
>>>
>>>data BinTree a = Node BinTree a BinTree a | EmptyBinTree deriving Show
>>>
>>>b1 = (Node (BinTree 3) EmptyBinTree)
>>>
>>>
>>>
>>>please help
>>>
>>>
>>>-kak
>>>
>>>
>>>_______________________________________________
>>>Beginners mailing list
>>>[email protected]
>>>http://www.haskell.org/mailman/listinfo/beginners
>>>
>>>
>
>
>
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