Re: [Haskell-beginners] error: Not in scope: data constructor `BinTree'

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 To: Kak Dod Cc: Tom Murphy ; "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" 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 To: Kak Dod Cc: Kyle Murphy ; "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 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 To: Kak Dod Cc: "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" 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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