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 <orclev@gmail.com> To: Kak Dod <kak.dod2008@yahoo.com> Cc: Tom Murphy <amindfv@gmail.com>; "beginners@haskell.org" <beginners@haskell.org> 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" <kak.dod2008@yahoo.com> 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 <amindfv@gmail.com> To: Kak Dod <kak.dod2008@yahoo.com> Cc: Kyle Murphy <orclev@gmail.com>; "beginners@haskell.org" <beginners@haskell.org> 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 <kak.dod2008@yahoo.com> 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 <orclev@gmail.com> To: Kak Dod <kak.dod2008@yahoo.com> Cc: "beginners@haskell.org" <beginners@haskell.org> 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" <kak.dod2008@yahoo.com> 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
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