A "show" error

bahadýr altan

11 Mar 2012 11 Mar '12

7:10 p.m.

Hi, I'm trying to process on a tree with this function : f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2) and my tree declaration is this : data Tree = Empty | Branch Integer Tree Tree deriving (Show) And I'm getting this error : Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree) I'll be happy if you help me to get rid of this error..

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Ozgur Akgun

11 Mar 11 Mar

7:26 p.m.

Hi again, What interpreter do you use? With ghci, I don't get any errors. *Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) (12,15,Empty,Empty,28,Empty,Empty) On 11 March 2012 19:10, bahadýr altan wrote:

...

Hi, I'm trying to process on a tree with this function :

f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2)

and my tree declaration is this :

data Tree = Empty | Branch Integer Tree Tree deriving (Show)

And I'm getting this error :

Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree)

I'll be happy if you help me to get rid of this error..

-- Ozgur Akgun

Adrien Haxaire

7:43 p.m.

On Sun, Mar 11, 2012 at 07:26:02PM +0000, Ozgur Akgun wrote:

...

Hi again,

What interpreter do you use? With ghci, I don't get any errors.

*Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) (12,15,Empty,Empty,28,Empty,Empty)

Hi, Me neither, no error on GHCi 7.4.1 on ArchLinux. Prelude> data Tree = Empty | Branch Integer Tree Tree deriving (Show) Prelude> let f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2) Prelude> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) (12,15,Empty,Empty,28,Empty,Empty) HTH, Adrien -- Adrien Haxaire www.adrienhaxaire.org | @adrienhaxaire

bahadýr altan

8 p.m.

I use Hugs. And I must use it... ________________________________ From: Ozgur Akgun To: bahadýr altan Cc: "beginners@haskell.org" Sent: Sunday, 11 March 2012, 21:26 Subject: Re: [Haskell-beginners] A "show" error Hi again, What interpreter do you use? With ghci, I don't get any errors. *Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) (12,15,Empty,Empty,28,Empty,Empty) On 11 March 2012 19:10, bahadýr altan wrote: Hi,

...

I'm trying to process on a tree with this function :

f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2)

and my tree declaration is this :

data Tree = Empty | Branch Integer Tree Tree deriving (Show)

And I'm getting this error :

Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree)

I'll be happy if you help me to get rid of this error.. -- Ozgur Akgun

Brandon Allbery

12 Mar 12 Mar

1:20 a.m.

On Sun, Mar 11, 2012 at 16:00, bahadýr altan wrote:

...

I use Hugs. And I must use it...

That's ... unfortunate. Use smaller tuples, then; I believe 6 is the limit for its Show and Read instances. Or define your own result ADT and derive a Show instance for it. -- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

Lyndon Maydwell

11 Apr 11 Apr

10:49 p.m.

Is 6 actually a limit, or is that just what is already defined? Could a new Show instance for 7-tuples be defined? On Mon, Mar 12, 2012 at 9:20 AM, Brandon Allbery wrote:

...

On Sun, Mar 11, 2012 at 16:00, bahadýr altan wrote:

...
I use Hugs. And I must use it...

That's ... unfortunate. Use smaller tuples, then; I believe 6 is the limit for its Show and Read instances. Or define your own result ADT and derive a Show instance for it.

-- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

Brandon Allbery

12 Apr 12 Apr

1:07 a.m.

On Wed, Apr 11, 2012 at 18:49, Lyndon Maydwell wrote:

...

Is 6 actually a limit, or is that just what is already defined? Could a new Show instance for 7-tuples be defined?

It can be defined, it's just a pain in the butt. GHC predefines Show for up to something like 15-tuples, I think. -- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

Adrien Haxaire

11 Mar 11 Mar

7:26 p.m.

On Sun, Mar 11, 2012 at 07:10:28PM +0000, bahadýr altan wrote:

...

Hi, I'm trying to process on a tree with this function :

f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2)

and my tree declaration is this :

data Tree = Empty | Branch Integer Tree Tree deriving (Show)

And I'm getting this error :

Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree)

I'll be happy if you help me to get rid of this error..

Hello, Dit you try to derive it automatically, by adding 'deriving (Show)' after its declaration? Otherwise you need to define it manually I'm afraid. -- Adrien Haxaire www.adrienhaxaire.org | @adrienhaxaire

Adrien Haxaire

7:34 p.m.

Oh sorry I just realized you did ! On Sun, Mar 11, 2012 at 07:10:28PM +0000, bahadýr altan wrote:

...

Hi, I'm trying to process on a tree with this function :

f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2)

and my tree declaration is this :

data Tree = Empty | Branch Integer Tree Tree deriving (Show)

And I'm getting this error :

Main> f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree)

I'll be happy if you help me to get rid of this error..

...

_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

-- Adrien Haxaire www.adrienhaxaire.org | @adrienhaxaire

Brandon Allbery

7:42 p.m.

On Sun, Mar 11, 2012 at 15:10, bahadýr altan wrote:

...

ERROR - Cannot find "show" function for: *** Expression : f (Branch 12 (Branch 15 Empty Empty) (Branch 28 Empty Empty)) *** Of type : (Integer,Integer,Tree,Tree,Integer,Tree,Tree)

Hugs apparently doesn't have a Show instance for 7-tuples. Note that Hugs is quite old and not very well supported at this point; you should probably be using ghc / ghci instead. -- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

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Adrien Haxaire
bahadýr altan
Brandon Allbery
Lyndon Maydwell
Ozgur Akgun

A "show" error

bahadýr altan

bahadýr altan

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