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

[Kyle Murphy]

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 at 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 at gmail.com>
> *To:* Kak Dod <kak.dod2008 at yahoo.com>
> *Cc:* Kyle Murphy <orclev at gmail.com>; "beginners at haskell.org" <
> beginners at 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 at 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 at gmail.com>
> > To: Kak Dod <kak.dod2008 at yahoo.com>
> > Cc: "beginners at haskell.org" <beginners at 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 at 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
> >>
> >>
> >>_______________________________________________
> >>Beginners mailing list
> >>Beginners at haskell.org
> >>http://www.haskell.org/mailman/listinfo/beginners
> >>
> >>
>
>
>
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