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Today's Topics:
1. Re: A "show" error (Adrien Haxaire)
2. Re: A "show" error (Adrien Haxaire)
3. Re: A "show" error (Brandon Allbery)
4. Re: A "show" error (Adrien Haxaire)
5. Re: A "show" error (bahad?r altan)
6. Re: A "show" error (Brandon Allbery)
7. populating a bloom filter; stymied by ST monad (Joey Hess)
----------------------------------------------------------------------
Message: 1
Date: Sun, 11 Mar 2012 20:26:54 +0100
From: Adrien Haxaire <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: [email protected]
Message-ID: <20120311192654.GA4231@arch>
Content-Type: text/plain; charset=iso-8859-1
On Sun, Mar 11, 2012 at 07:10:28PM +0000, bahad?r 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
------------------------------
Message: 2
Date: Sun, 11 Mar 2012 20:34:13 +0100
From: Adrien Haxaire <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: [email protected]
Message-ID: <20120311193413.GB4231@arch>
Content-Type: text/plain; charset=iso-8859-1
Oh sorry I just realized you did !
On Sun, Mar 11, 2012 at 07:10:28PM +0000, bahad?r 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
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
--
Adrien Haxaire
www.adrienhaxaire.org | @adrienhaxaire
------------------------------
Message: 3
Date: Sun, 11 Mar 2012 15:42:29 -0400
From: Brandon Allbery <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: bahad?r altan <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<cakfcl4x7o7u8kdgq6erlm0tee4oynmnt3nqqsqccvvq+23a...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
On Sun, Mar 11, 2012 at 15:10, bahad?r altan <[email protected]> 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 [email protected]
wandering unix systems administrator (available) (412) 475-9364 vm/sms
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Message: 4
Date: Sun, 11 Mar 2012 20:43:13 +0100
From: Adrien Haxaire <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: [email protected]
Message-ID: <20120311194313.GC4231@arch>
Content-Type: text/plain; charset=us-ascii
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
------------------------------
Message: 5
Date: Sun, 11 Mar 2012 20:00:34 +0000 (GMT)
From: bahad?r altan <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: Ozgur Akgun <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
I use Hugs. ?And I must use it...
________________________________
From: Ozgur Akgun <[email protected]>
To: bahad?r altan <[email protected]>
Cc: "[email protected]" <[email protected]>
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, bahad?r altan <[email protected]> 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
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Message: 6
Date: Sun, 11 Mar 2012 21:20:49 -0400
From: Brandon Allbery <[email protected]>
Subject: Re: [Haskell-beginners] A "show" error
To: bahad?r altan <[email protected]>
Cc: "[email protected]" <[email protected]>
Message-ID:
<CAKFCL4WB=aicgyrxlfhzwqekavgsupzfmxhzdgz9ylbqgrq...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
On Sun, Mar 11, 2012 at 16:00, bahad?r altan <[email protected]> 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 [email protected]
wandering unix systems administrator (available) (412) 475-9364 vm/sms
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------------------------------
Message: 7
Date: Mon, 12 Mar 2012 02:38:45 -0400
From: Joey Hess <[email protected]>
Subject: [Haskell-beginners] populating a bloom filter; stymied by ST
monad
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
I have a potentially very large number of values to feed into a bloom
filter. They're coming from IO:
getValues :: (v -> k -> k) -> k -> IO k
getValues update initial = go initial =<< gen
where
go v [] = return v
go v (f:fs) = do
x <- val f
go (maybe v (`update` v) x) fs
gen = undefined
val f = undefined
This streams lazily, but if I build a list (getValues (:) []),
the laziness is lost; the whole list is constructed and returned
before any of it can be used. Which uses too much memory of course.
So I can't use Data.BloomFilter.fromListB.
Seems I need to do something like this:
let filter = newMB (cheapHashes 13) 33554432 --- sized for 1 million items
filter' <- unsafeFreezeMB <$> getValues insertMB filter
Except this won't work, the mutable bloom filter uses the ST monad.
And I cannot see a way to combine the three "MB" functions into a
single computation in the same ST monad.
Perhaps stToIO to is what I need, but I can't work out how to use it.
Help?
--
see shy jo
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