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Today's Topics:
1. Re: Issue with lazy eval + trace (Daniel Fischer)
2. Re: Issue with lazy eval + trace (Hugo Ferreira)
3. Re: Issue with lazy eval + trace (Daniel Fischer)
4. Search for docs on operator '<+>'. (Allen S. Rout)
5. Re: Search for docs on operator '<+>'. (David McBride)
6. Re: Search for docs on operator '<+>'. (Daniel Fischer)
7. Re: Search for docs on operator '<+>'. (Brent Yorgey)
8. Couple of problems with leksah (Peter Hall)
9. Re: Search for docs on operator '<+>'. (Jared Wigmore)
10. Re: Couple of problems with leksah (Daniel Fischer)
----------------------------------------------------------------------
Message: 1
Date: Mon, 7 Nov 2011 14:47:14 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Issue with lazy eval + trace
To: beginners@haskell.org
Message-ID: <201111071447.14845.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="iso-8859-1"
On Monday 07 November 2011, 09:41:24, Hugo Ferreira wrote:
> Hello,
>
> I am using "import Debug.Trace" to debug some code but it is
> not working as expected. I believe this is due to lazy evaluation.
> But I cannot see how I can circumvent it. To exemplify I have
> the following function:
>
> tagFun :: (POSTags -> Tag) -> POSTags -> POSTags
> tagFun f corpus = Z.foldlz' tag Z.empty corpus
> where
> tag acc z = Z.insert newTag acc
> where
> (token, correctTag, _proposdTag) = trace "cursor " Z.cursor z
> proposed = trace "proposed tag" (f z)
> newTag = ( token, correctTag, proposed )
>
>
> If I place tracing at:
>
> tag acc z = trace ("tag "++token++" = "++ show newTag) Z.insert
> newTag acc
>
> then it works ok. However the lines
>
> (token, correctTag, _proposdTag) = trace "cursor " Z.cursor z
> proposed = trace "proposed tag" (f z)
>
> don't work. They only appear once. I assume they should appear with
> every element in the zipper. Can anyone explain why?
You're compiling with optimisations, aren't you?
You need the trace strings to depend on the input, otherwise the optimiser
sees no reason to repeat the work. (The constant part is lifted out of the
lambda, a consequence of unsafePerformIO.)
The line `trace "cursor " Z.cursor z' actually shouldn't print multiple
traces even without optimisations, since it's
(trace "cursor " Z.cursor) z
so the trace applies to the evaluation of the function Z.cursor, which
should only be done once.
------------------------------
Message: 2
Date: Mon, 07 Nov 2011 16:11:10 +0000
From: Hugo Ferreira <h...@inescporto.pt>
Subject: Re: [Haskell-beginners] Issue with lazy eval + trace
To: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Cc: beginners@haskell.org
Message-ID: <4eb8031e.1040...@inescporto.pt>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 11/07/2011 01:47 PM, Daniel Fischer wrote:
> On Monday 07 November 2011, 09:41:24, Hugo Ferreira wrote:
>> Hello,
>>
>> I am using "import Debug.Trace" to debug some code but it is
>> not working as expected. I believe this is due to lazy evaluation.
>> But I cannot see how I can circumvent it. To exemplify I have
>> the following function:
>>
>> tagFun :: (POSTags -> Tag) -> POSTags -> POSTags
>> tagFun f corpus = Z.foldlz' tag Z.empty corpus
>> where
>> tag acc z = Z.insert newTag acc
>> where
>> (token, correctTag, _proposdTag) = trace "cursor " Z.cursor z
>> proposed = trace "proposed tag" (f z)
>> newTag = ( token, correctTag, proposed )
>>
>>
>> If I place tracing at:
>>
>> tag acc z = trace ("tag "++token++" = "++ show newTag) Z.insert
>> newTag acc
>>
>> then it works ok. However the lines
>>
>> (token, correctTag, _proposdTag) = trace "cursor " Z.cursor z
>> proposed = trace "proposed tag" (f z)
>>
>> don't work. They only appear once. I assume they should appear with
>> every element in the zipper. Can anyone explain why?
>
> You're compiling with optimisations, aren't you?
Not that I am aware of. I did not set up any compilation flags in the
cabal file.
> You need the trace strings to depend on the input, otherwise the optimiser
> sees no reason to repeat the work. (The constant part is lifted out of the
> lambda, a consequence of unsafePerformIO.)
>
Ok, I understand now. Should have appended some output to the trace
output string (thats what the working trace does).
> The line `trace "cursor " Z.cursor z' actually shouldn't print multiple
> traces even without optimisations, since it's
>
> (trace "cursor " Z.cursor) z
>
Ooops, thats a bug 8-(
> so the trace applies to the evaluation of the function Z.cursor, which
> should only be done once.
>
Ok, think I got it.
Thank you,
Hugo F.
------------------------------
Message: 3
Date: Mon, 7 Nov 2011 17:56:35 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Issue with lazy eval + trace
To: Hugo Ferreira <h...@inescporto.pt>
Cc: beginners@haskell.org
Message-ID: <201111071756.35570.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="iso-8859-1"
On Monday 07 November 2011, 17:11:10, Hugo Ferreira wrote:
> > You're compiling with optimisations, aren't you?
>
> Not that I am aware of. I did not set up any compilation flags in the
> cabal file.
cabal defaults to compiling with -O unless otherwise specified
($ cabal build -v2 emits the command lines used to build, if you want to
check), so you most likely do.
------------------------------
Message: 4
Date: Mon, 07 Nov 2011 13:16:51 -0500
From: "Allen S. Rout" <a...@ufl.edu>
Subject: [Haskell-beginners] Search for docs on operator '<+>'.
To: beginners@haskell.org
Message-ID: <j997ak$5mr$1...@dough.gmane.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Google seems to barf on '<+>'. I've found a haskell "list of
operators", and it's not mentioned.
Could some kind soul point me at documentation for this thing?
- Allen S. Rout
------------------------------
Message: 5
Date: Mon, 7 Nov 2011 13:26:00 -0500
From: David McBride <toa...@gmail.com>
Subject: Re: [Haskell-beginners] Search for docs on operator '<+>'.
To: "Allen S. Rout" <a...@ufl.edu>
Cc: beginners@haskell.org
Message-ID:
<CAN+Tr42byh=R=w-gqzuaqxup1qdxjhyx2jokgrvjcdnejyw...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
http://www.haskell.org/hoogle/?hoogle=%3C%2B%3E
On Mon, Nov 7, 2011 at 1:16 PM, Allen S. Rout <a...@ufl.edu> wrote:
>
>
> Google seems to barf on '<+>'. ? I've found a haskell "list of operators",
> and it's not mentioned.
>
> Could some kind soul point me at documentation for this thing?
>
> - Allen S. Rout
>
>
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 6
Date: Mon, 7 Nov 2011 19:39:54 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Search for docs on operator '<+>'.
To: beginners@haskell.org
Cc: "Allen S. Rout" <a...@ufl.edu>
Message-ID: <201111071939.54282.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="iso-8859-1"
On Monday 07 November 2011, 19:16:51, Allen S. Rout wrote:
> Google seems to barf on '<+>'. I've found a haskell "list of
> operators", and it's not mentioned.
>
> Could some kind soul point me at documentation for this thing?
Try hoogle:
http://www.haskell.org/hoogle/?hoogle=%3C%2B%3E
(a few hits, searches only a restricted number of packages)
or hayoo:
http://holumbus.fh-wedel.de/hayoo/hayoo.html?query=%3C%2B%3E
(none found for this one :-( )
Or look at the ghc docs for stuff in the basic libraries:
http://haskell.org/ghc/docs/7.0-latest/html/libraries/doc-index-60.html
You may be looking for a different <+>, though. Unfortunately, afaik,
there's no global hackage index of names.
------------------------------
Message: 7
Date: Mon, 7 Nov 2011 14:47:40 -0500
From: Brent Yorgey <byor...@seas.upenn.edu>
Subject: Re: [Haskell-beginners] Search for docs on operator '<+>'.
To: beginners@haskell.org
Message-ID: <20111107194740.ga8...@seas.upenn.edu>
Content-Type: text/plain; charset=us-ascii
On Mon, Nov 07, 2011 at 01:16:51PM -0500, Allen S. Rout wrote:
>
>
> Google seems to barf on '<+>'. I've found a haskell "list of
> operators", and it's not mentioned.
>
> Could some kind soul point me at documentation for this thing?
>
> - Allen S. Rout
In theory there could be many different definitions of <+> in many
different packages. Off the top of my head I do not know of a
"standard" meaning for it. Why are you looking for it? Did you see
it used somewhere in particular?
-Brent
------------------------------
Message: 8
Date: Tue, 8 Nov 2011 00:59:47 +0000
From: Peter Hall <peter.h...@memorphic.com>
Subject: [Haskell-beginners] Couple of problems with leksah
To: beginners@haskell.org
Message-ID:
<CAA6hAk4w2TnPtX=dv2DvrupPH0URi=5kgoszuxco_f56fcr...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
I didn't get any response on the Leksah forum, so I hope it's ok to ask here.
First problem, I keep seeing this in the error log:
> Setup: You need to re-run the 'configure' command. The version of Cabal being
> used has changed (was Cabal-1.10.2.0, now Cabal-1.10.1.0). Additionally the
> compiler is different (was ghc-6.12, now ghc-7.0) which is probably the cause
> of the problem.
When I run configure, it just prints:
> Resolving dependencies...
> Configuring pokercalc-0.0.1...
But it doesn't fix anything.
The other problem is when I try to update cabal:
> cabal install leksah
Resolving dependencies...
cabal: cannot configure haddock-2.9.4. It requires ghc >=7.2 && <7.4
There is no available version of ghc that satisfies >=7.2 && <7.4
I'm using Haskell Platform 2011.2.0.1 for Mac OS X 10.6
Any ideas?
Peter
------------------------------
Message: 9
Date: Tue, 8 Nov 2011 09:03:12 +0800
From: Jared Wigmore <jared.wigm...@gmail.com>
Subject: Re: [Haskell-beginners] Search for docs on operator '<+>'.
To: Brent Yorgey <byor...@seas.upenn.edu>
Cc: beginners@haskell.org
Message-ID:
<CACt4PuqC93TP8DKVRVL5u8p3YsOhEEbYOT7MbqjCYt=gii2...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi,
It's part of the "Arrows" system, see: http://www.haskell.org/arrows/
and
http://hackage.haskell.org/packages/archive/base/latest/doc/html/Control-Arrow.html
On Tue, Nov 8, 2011 at 3:47 AM, Brent Yorgey <byor...@seas.upenn.edu> wrote:
> On Mon, Nov 07, 2011 at 01:16:51PM -0500, Allen S. Rout wrote:
>>
>>
>> Google seems to barf on '<+>'. ? I've found a haskell "list of
>> operators", and it's not mentioned.
>>
>> Could some kind soul point me at documentation for this thing?
>>
>> - Allen S. Rout
>
> In theory there could be many different definitions of <+> in many
> different packages. ?Off the top of my head I do not know of a
> "standard" meaning for it. ?Why are you looking for it? ?Did you see
> it used somewhere in particular?
>
> -Brent
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
--
Jared Wigmore <jared.wigm...@gmail.com>
------------------------------
Message: 10
Date: Tue, 8 Nov 2011 02:18:34 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Couple of problems with leksah
To: beginners@haskell.org, peter.h...@memorphic.com
Message-ID: <201111080218.34270.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="iso-8859-1"
On Tuesday 08 November 2011, 01:59:47, Peter Hall wrote:
> I didn't get any response on the Leksah forum, so I hope it's ok to ask
> here.
Sure. Anything Haskell-related is okay to ask here.
>
> First problem, I keep seeing this in the error log:
> > Setup: You need to re-run the 'configure' command. The version of
> > Cabal being used has changed (was Cabal-1.10.2.0, now
> > Cabal-1.10.1.0). Additionally the compiler is different (was
> > ghc-6.12, now ghc-7.0) which is probably the cause of the problem.
>
> When I run configure, it just prints:
> > Resolving dependencies...
> > Configuring pokercalc-0.0.1...
>
> But it doesn't fix anything.
Sorry, no idea for that one.
>
> The other problem is when I try to update cabal:
> > cabal install leksah
>
> Resolving dependencies...
> cabal: cannot configure haddock-2.9.4. It requires ghc >=7.2 && <7.4
> There is no available version of ghc that satisfies >=7.2 && <7.4
haddock-2.9.4 is exclusively for ghc-7.2, with ghc-7.0, you need
haddock-2.9.2, try
$ cabal install leksah --constraint="haddock < 2.9.4"
>
> I'm using Haskell Platform 2011.2.0.1 for Mac OS X 10.6
> Any ideas?
>
> Peter
------------------------------
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