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Today's Topics:
1. how to modify show for a list of certain types (Manfred Lotz)
2. Re: how to modify show for a list of certain types
(Daniel Fischer)
3. haskell on the jvm? (Mike Meyer)
4. Re: Question about functors (or maybe not...)
(Patrick LeBoutillier)
5. Re: Haskell Platform and GHC 7.0.3 (Magnus Therning)
6. Re: haskell on the jvm? (Krzysztof Skrz?tnicki)
----------------------------------------------------------------------
Message: 1
Date: Sat, 2 Apr 2011 15:32:07 +0200
From: Manfred Lotz <manfred.l...@arcor.de>
Subject: [Haskell-beginners] how to modify show for a list of certain
types
To: beginners@haskell.org
Message-ID: <20110402153207.23f2c...@arcor.com>
Content-Type: text/plain; charset=US-ASCII
Hi there,
I have a list of say type Record which I write to a file and
read back from the file if required.
The list's content is a single line in the file it doesn't matter how
many records the list contains.
I would like to modify show for type Record in a way that show does
work like the normal show but additionally adds a newline at the end of
the string.
I'm a bit lost how to do that. Any idea?
--
Manfred
------------------------------
Message: 2
Date: Sat, 2 Apr 2011 15:51:33 +0200
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] how to modify show for a list of
certain types
To: beginners@haskell.org
Cc: Manfred Lotz <manfred.l...@arcor.de>
Message-ID: <201104021551.34557.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="iso-8859-1"
On Saturday 02 April 2011 15:32:07, Manfred Lotz wrote:
> Hi there,
> I have a list of say type Record which I write to a file and
> read back from the file if required.
>
> The list's content is a single line in the file it doesn't matter how
> many records the list contains.
>
> I would like to modify show for type Record in a way that show does
> work like the normal show but additionally adds a newline at the end of
> the string.
>
> I'm a bit lost how to do that. Any idea?
There's a showList function in the Show class, you can use that to define
non-standard list displays (as it's done for [Char] = String).
You cannot then derive the Show instance, which may be a minor
inconvenience or a major pain.
In the latter case, you could define a newtype,
newtype RecordList = RL [Record]
instance Show RecordList where
show (RL xs) = unlines (map show xs)
and use that to display when you want things on separate lines.
Or you could modify the function used to writing the file, instead of
hPutStrLn fileHandle (show recordList)
mapM_ (hPrint fileHandle) recordList
------------------------------
Message: 3
Date: Sat, 2 Apr 2011 09:59:22 -0400
From: Mike Meyer <m...@mired.org>
Subject: [Haskell-beginners] haskell on the jvm?
To: beginners@haskell.org
Message-ID: <20110402095922.29242...@bhuda.mired.org>
Content-Type: text/plain; charset=US-ASCII
Google didn't turn up anything, so...
Is there any way to compile haskell to JVM bytecodes? Dalvik, even? A
gcc front end, maybe?
Thanks,
<mike
--
Mike Meyer <m...@mired.org> http://www.mired.org/consulting.html
Independent Software developer/SCM consultant, email for more information.
O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
------------------------------
Message: 4
Date: Sat, 2 Apr 2011 10:57:28 -0400
From: Patrick LeBoutillier <patrick.leboutill...@gmail.com>
Subject: Re: [Haskell-beginners] Question about functors (or maybe
not...)
To: Felipe Almeida Lessa <felipe.le...@gmail.com>
Cc: beginners <beginners@haskell.org>
Message-ID: <banlktiny+kjbr4hm+hfmowg8n7sn0x3...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Felipe,
> You can write your own plain old functions:
>
> mapChord :: (Note -> Note) -> Chord -> Chord
> mapChord f (Chord q n) = Chord q (f n)
>
> mapScale :: (Note -> Note) -> Scale -> Scale
> mapScale f (Scale q n) = Scale q (f n)
>
> You can also create your own type class, if that's convenient for you
>
> class NoteMap a where
> ?noteMap :: (Note -> Note) -> a -> a
>
> instance NoteMap Chord where noteMap = mapChord
> instance NoteMap Scale where noteMap = mapScale
Initially I didn't realize how powerful this approach could be, but
once you have noteMap then most of the functions for altering Notes
can then be used on the other types, *without* having to make them
(the functions I mean) be part of the typeclass definition.
This seems obvious but I hadn't really noticed it until now...
Thanks a lot,
Patrick
> HTH, =)
>
> --
> Felipe.
>
--
=====================
Patrick LeBoutillier
Rosem?re, Qu?bec, Canada
------------------------------
Message: 5
Date: Sat, 2 Apr 2011 20:28:53 +0100
From: Magnus Therning <mag...@therning.org>
Subject: Re: [Haskell-beginners] Haskell Platform and GHC 7.0.3
To: beginners@haskell.org
Message-ID: <20110402192853.GA5227@ohann>
Content-Type: text/plain; charset="us-ascii"
On Fri, Apr 01, 2011 at 01:35:45PM -0500, Forrest Cahoon wrote:
> On Fri, Apr 1, 2011 at 10:33 AM, Alba Marchisio
> <alba.marchi...@gmail.com> wrote:
> > Sorry I'm new and probably this post is out of topic, but my question is:
> > when a Haskell Platform integrated with GHC 7.0.3?
> > Thanks
> > Alba.
>
> The current 2011.2.0.0 version linked from
> http://hackage.haskell.org/platform/ does. It took them a while to
> update that link, but it's there now.
No, it lists GHC 7.0.2. I don't think we'll see 7.0.3 in HP for at
least a few months (2011.4.0.0).
/M
--
Magnus Therning OpenPGP: 0xAB4DFBA4
email: mag...@therning.org jabber: mag...@therning.org
twitter: magthe http://therning.org/magnus
I invented the term Object-Oriented, and I can tell you I did not have
C++ in mind.
-- Alan Kay
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Message: 6
Date: Sat, 2 Apr 2011 23:31:28 +0200
From: Krzysztof Skrz?tnicki <gte...@gmail.com>
Subject: Re: [Haskell-beginners] haskell on the jvm?
To: Mike Meyer <m...@mired.org>
Cc: beginners@haskell.org
Message-ID: <BANLkTi=ozexcgwpmksocce+6j85bl6z...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
There is JHC: http://repetae.net/computer/jhc/
<http://repetae.net/computer/jhc/>It compiles Haskell into standard
compliant C code which can be easily compiled with GCC. Be aware though not
all libraries are going to work with it. In particular there are many
language extensions which aren't implemented and some libraries may depend
upon them.
Best regards,
Krzysztof Skrz?tnicki
On Sat, Apr 2, 2011 at 15:59, Mike Meyer <m...@mired.org> wrote:
> Google didn't turn up anything, so...
>
> Is there any way to compile haskell to JVM bytecodes? Dalvik, even? A
> gcc front end, maybe?
>
> Thanks,
> <mike
> --
> Mike Meyer <m...@mired.org>
> http://www.mired.org/consulting.html
> Independent Software developer/SCM consultant, email for more information.
>
> O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
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