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Today's Topics:
1. Re: cmath Install troubles (Brandon Allbery)
2. Re: Seq question (Tim Perry)
3. Re: Seq question (Daniel Fischer)
4. Re: cmath Install troubles (Tom Murphy)
5. Two questions for a production project... (Mike Meyer)
6. Re: cmath Install troubles (Tom Murphy)
7. Re: Two questions for a production project... (Michael Orlitzky)
----------------------------------------------------------------------
Message: 1
Date: Thu, 19 Apr 2012 16:31:33 -0400
From: Brandon Allbery <[email protected]>
Subject: Re: [Haskell-beginners] cmath Install troubles
To: Tom Murphy <[email protected]>
Cc: beginners <[email protected]>
Message-ID:
<CAKFCL4WSHJz9Vn6t1cc_5QU67j=immuscgczfujlawkobk8...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
On Thu, Apr 19, 2012 at 06:31, Tom Murphy <[email protected]> wrote:
> So does nobody use cmath anymore? I'm trying to install the latest
> version (which is from 2008).
At a guess, it's well supported on Linux and (since it's dons) NetBSD. OS
X and Windows, probably not so well tested.
--
brandon s allbery [email protected]
wandering unix systems administrator (available) (412) 475-9364 vm/sms
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Message: 2
Date: Thu, 19 Apr 2012 14:13:48 -0700
From: Tim Perry <[email protected]>
Subject: Re: [Haskell-beginners] Seq question
To: [email protected]
Message-ID:
<CAFVgASUyEfyRbarCpSUQfAPz1wCmdEPTk09DSp7b6Oc=xk1...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Henk-Jan van Tuly is correct. Oops! Sorry I was mis-informed. By the way,
there is an excellent post about this topic on StackOverflow.com. It
covers, seq, weak-head-normal-form, normal form, and thunks. See here:
http://stackoverflow.com/questions/6872898/haskell-what-is-weak-head-normal-form/6889335#6889335
Hope that makes up for my earlier comment.
Tim
On Thu, Apr 19, 2012 at 2:31 AM, Henk-Jan van Tuyl <[email protected]>wrote:
> On Wed, 18 Apr 2012 16:45:05 +0200, Brent Yorgey <[email protected]>
> wrote:
>
> On Tue, Apr 17, 2012 at 02:41:15PM -0700, Tim Perry wrote:
>>
>>> seq evaluates to Weak Head Normal Form (WHNF). WHNF is the first
>>> contructor. So your use of seq only evaluates the first number and the
>>> cons. I.E., it evaluates to:
>>> s:(Thunk)
>>>
>>
>> Actually, it doesn't even force the first number. You just get
>>
>> Thunk : Thunk
>>
>>
> A nice way to demonstrate this, is the following GHCi session:
> Prelude> undefined `seq` print "OK"
> *** Exception: Prelude.undefined
> Prelude> [undefined] `seq` print "OK"
> "OK"
>
>
> Regards,
> Henk-Jan van Tuyl
>
>
> --
> http://Van.Tuyl.eu/
> http://members.chello.nl/**hjgtuyl/tourdemonad.html<http://members.chello.nl/hjgtuyl/tourdemonad.html>
> Haskell programming
> --
>
>
> ______________________________**_________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/**mailman/listinfo/beginners<http://www.haskell.org/mailman/listinfo/beginners>
>
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Message: 3
Date: Fri, 20 Apr 2012 00:23:22 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] Seq question
To: [email protected]
Message-ID: <[email protected]>
Content-Type: Text/Plain; charset="utf-8"
On Thursday 19 April 2012, 23:13:48, Tim Perry wrote:
> Henk-Jan van Tuly is correct. Oops! Sorry I was mis-informed.
Note, however, that in the case here, the data-dependencies force the
evaluation of the first number in order to determine the outermost
constructor.
So actually, your
> So your use of seq only evaluates the first number and
> the cons. I.E., it evaluates to:
> s:(Thunk)
was factually correct (in this special case).
> By the
> way, there is an excellent post about this topic on StackOverflow.com.
> It covers, seq, weak-head-normal-form, normal form, and thunks. See
> here:
> http://stackoverflow.com/questions/6872898/haskell-what-is-weak-head-no
> rmal-form/6889335#6889335
>
>
> Hope that makes up for my earlier comment.
>
> Tim
>
> On Thu, Apr 19, 2012 at 2:31 AM, Henk-Jan van Tuyl
<[email protected]>wrote:
> > On Wed, 18 Apr 2012 16:45:05 +0200, Brent Yorgey
> > <[email protected]>
> >
> > wrote:
> > On Tue, Apr 17, 2012 at 02:41:15PM -0700, Tim Perry wrote:
> >>> seq evaluates to Weak Head Normal Form (WHNF). WHNF is the first
> >>> contructor. So your use of seq only evaluates the first number and
> >>> the cons. I.E., it evaluates to:
> >>> s:(Thunk)
> >>
> >> Actually, it doesn't even force the first number. You just get
> >>
> >> Thunk : Thunk
> >
> > A nice way to demonstrate this, is the following GHCi session:
> > Prelude> undefined `seq` print "OK"
> > *** Exception: Prelude.undefined
> > Prelude> [undefined] `seq` print "OK"
> > "OK"
> >
> > Regards,
> > Henk-Jan van Tuyl
------------------------------
Message: 4
Date: Thu, 19 Apr 2012 18:29:39 -0400
From: Tom Murphy <[email protected]>
Subject: Re: [Haskell-beginners] cmath Install troubles
To: Brandon Allbery <[email protected]>
Cc: beginners <[email protected]>
Message-ID:
<cao9q0tvzxtsj_bf5hpul5g5ojyxcuq-vhzzu9wd3gixzx0g...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
cmath doesn't build now, but I successfully installed hsc3 (which
depends on cmath) on my computer less than 6 months ago. Same CPU and
OS version, but different ghc/HP, and possibly different XCode.
Also:
Some other packages which have the same FFI C-include style build fine
on my machine. Some which even include math.h. For example:
- strptime
- mp3decoder
So maybe it's not a problem involving not having -fvia-c?
Tom
On 4/19/12, Brandon Allbery <[email protected]> wrote:
> On Thu, Apr 19, 2012 at 06:31, Tom Murphy <[email protected]> wrote:
>
>> So does nobody use cmath anymore? I'm trying to install the latest
>> version (which is from 2008).
>
>
> At a guess, it's well supported on Linux and (since it's dons) NetBSD. OS
> X and Windows, probably not so well tested.
>
> --
> brandon s allbery [email protected]
> wandering unix systems administrator (available) (412) 475-9364 vm/sms
>
------------------------------
Message: 5
Date: Thu, 19 Apr 2012 19:40:02 -0400
From: Mike Meyer <[email protected]>
Subject: [Haskell-beginners] Two questions for a production project...
To: [email protected] <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=US-ASCII
I've got a project coming up that I could use haskell for, providing I
can convince myself that it's appropriate. The critical question is:
Anyone using Haskell in a long-running production application? I'm
talking about something where the program would run for weeks or
months non-stop, with either multiple threads or multiple copies.
<mike
--
Mike Meyer <[email protected]> http://www.mired.org/
Independent Software developer/SCM consultant, email for more information.
O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
------------------------------
Message: 6
Date: Thu, 19 Apr 2012 22:03:18 -0400
From: Tom Murphy <[email protected]>
Subject: Re: [Haskell-beginners] cmath Install troubles
To: Brandon Allbery <[email protected]>
Cc: beginners <[email protected]>
Message-ID:
<CAO9Q0tUq+UorWfmTNFf=Am=kt4kq1hrlf1f61ezazitajet...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Also, is there a way that I could "short circuit" (in the "True || _ =
True" sense) the whole process of fixing this?
For example, cabal-install cmath on a machine with similar
architecture and OS, break out my SICP [0], and try to replicate
cabal's storage methods by hand?
Tom
[0] http://www.vex.net/~trebla/haskell/sicp.xhtml
On 4/19/12, Tom Murphy <[email protected]> wrote:
> cmath doesn't build now, but I successfully installed hsc3 (which
> depends on cmath) on my computer less than 6 months ago. Same CPU and
> OS version, but different ghc/HP, and possibly different XCode.
>
> Also:
>
> Some other packages which have the same FFI C-include style build fine
> on my machine. Some which even include math.h. For example:
> - strptime
> - mp3decoder
>
> So maybe it's not a problem involving not having -fvia-c?
>
>
> Tom
>
> On 4/19/12, Brandon Allbery <[email protected]> wrote:
>> On Thu, Apr 19, 2012 at 06:31, Tom Murphy <[email protected]> wrote:
>>
>>> So does nobody use cmath anymore? I'm trying to install the latest
>>> version (which is from 2008).
>>
>>
>> At a guess, it's well supported on Linux and (since it's dons) NetBSD.
>> OS
>> X and Windows, probably not so well tested.
>>
>> --
>> brandon s allbery
>> [email protected]
>> wandering unix systems administrator (available) (412) 475-9364
>> vm/sms
>>
>
------------------------------
Message: 7
Date: Thu, 19 Apr 2012 22:43:13 -0400
From: Michael Orlitzky <[email protected]>
Subject: Re: [Haskell-beginners] Two questions for a production
project...
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
On 04/19/2012 07:40 PM, Mike Meyer wrote:
> I've got a project coming up that I could use haskell for, providing I
> can convince myself that it's appropriate. The critical question is:
>
> Anyone using Haskell in a long-running production application? I'm
> talking about something where the program would run for weeks or
> months non-stop, with either multiple threads or multiple copies.
I have a rather stupid application that parses feeds from the Twitter
API. For each username given on the command line, it calls forkIO and
the new thread enters a recursive loop:
recurse x y z = do
...
recurse x y z
forever and ever.
Contrary to my expectations (I still basically don't know what I'm doing
in Haskell) it seems to run in constant space for months at a time.
------------------------------
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