Re: [Haskell-cafe] csv one-liner
Op woensdag 01-10-2008 om 18:59 uur [tijdzone -0700], schreef Jason Dusek: > Reply to all? No. Reply-to-list is a different thing. When you reply-to-all to a person who is in the list, the person gets two copies of the e-mail with different headers, which messes with filters and replies. Greetings. -- marcot Página: http://marcotmarcot.iaaeee.org/ Blog: http://marcotmarcot.blogspot.com/ Correio: [EMAIL PROTECTED] XMPP: [EMAIL PROTECTED] IRC: [EMAIL PROTECTED] Telefone: 25151920 Celular: 98116720 Endereço: Rua Turfa, 639/701 Prado 30410-370 Belo Horizonte/MG Brasil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Reply to all? -- _jsn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Op woensdag 01-10-2008 om 10:15 uur [tijdzone +0200], schreef Ketil Malde: > Derek Elkins <[EMAIL PROTECTED]> writes: > > >> parseCSVFromFile "in.csv" >>= return . either (const "error!") > > > Whenever you see this >>= return . f pattern think liftM or fmap or <$>. > > ...and "return . f >>= action" is just "action . f", no? Maybe you meant "return f >>= action" is the same as "action f". Greetings. -- marcot Página: http://marcotmarcot.iaaeee.org/ Blog: http://marcotmarcot.blogspot.com/ Correio: [EMAIL PROTECTED] XMPP: [EMAIL PROTECTED] IRC: [EMAIL PROTECTED] Telefone: 25151920 Celular: 98116720 Endereço: Rua Turfa, 639/701 Prado 30410-370 Belo Horizonte/MG Brasil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Op woensdag 01-10-2008 om 13:25 uur [tijdzone -0700], schreef Martin DeMello: > 2008/10/1 wman <[EMAIL PROTECTED]>: > > > > PS: Sorry, Andrew, that I first posted the reply directly to you, still > > getting used to the fact that gmail kindly replies to the user on whose > > behalf the message was sent, not to the list. > > I think that's a list setting, not a gmail one. The list could set reply-to, which is usually not very recommended in netiquettes. And gmail doesn't have a reply-to-list option, which is very useful when the lists doesn't set reply-to, like haskell-cafe. Greetings. -- marcot Página: http://marcotmarcot.iaaeee.org/ Blog: http://marcotmarcot.blogspot.com/ Correio: [EMAIL PROTECTED] XMPP: [EMAIL PROTECTED] IRC: [EMAIL PROTECTED] Telefone: 25151920 Celular: 98116720 Endereço: Rua Turfa, 639/701 Prado 30410-370 Belo Horizonte/MG Brasil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
(writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $ parseCSVFromFile "input.csv") Um... Does anybody else find it interesting that we are "showing the beauty of Haskell" by attempting to construct the most terse, cryptic, unmaintainable tangle of point-free code I don't agree at all! How could a pipeline like this possibly be more clearly expressed than by the pattern: readInputFile "input" >>= mungeStuff >>= writeOutputFile "output" interact pureMungeStuff After all, you're looking for oneliners, not real programs. interact $ either (error . show) (printCSV . map updateLine) . parseCSV "" Claus -- some people need a vacation ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
On Wed, Oct 1, 2008 at 10:40 PM, Andrew Coppin <[EMAIL PROTECTED]>wrote: > Maybe I should start a new tradition where Haskellers have a blob of > Haskell as their sig? > > (I can't *wait* to see what the luminaries such as dons, dcoutts and igloo > come up with...) > Some haskell equivalent of : (lambda(x)x x)x)x)x)x)x)x)x)) (lambda(x)(lambda(y)(x(x y) (lambda(x)(x)x)) (lambda()(printf "Greetings, Jos~n" ? ;-))) and seeing ketil's sig, i cannot keep to myself this beautiful bastardization of the "shoulders of giants" line which i found today: Most men stand on the shoulders of giants. Matthew Garrett stamps on the testicles of midgets. PS: it seems the list won't re-send the message to people to whom it was directly addressed. so to stay in my on-click lazy mode, i'm trying the reply-to-all button. In the case i start flooding your mailboxes, just kindly kick my butt. thx ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Andrew Coppin <[EMAIL PROTECTED]> writes: >> (writeFile "output.csv") =<< (liftM printCSV $ liftM (map >> updateLine) $ parseCSVFromFile "input.csv") > Um... Does anybody else find it interesting that we are "showing the > beauty of Haskell" by attempting to construct the most terse, cryptic, > unmaintainable tangle of point-free code I don't agree at all! How could a pipeline like this possibly be more clearly expressed than by the pattern: readInputFile "input" >>= mungeStuff >>= writeOutputFile "output" ? The OP asks for improvements, which got rid of a couple of gratuitous liftMs and such, but otherwise I think it's a pretty straightforward idiom. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
wman wrote: Thats why i put those quotation marks around that part of sequence ;-)) AFAIK one-liners never were about comprehensibility, just about what you can cram into one line of code. Any programmer should have no problems guessing what the line does does (even more so when looking at the "final" version without the abundant liftM's), the beauty of it lies in figuring how the heck it does what it does. And figuring that out should bring the "profound enlightenment experience; that experience which should make you a better programmer for the rest of your days, even if you never actually use Lisp -erm Haskell- itself a lot" (my apologies, P. Graham, for cannibalizing your words). I should probably get myself a signature stating that i will explicitly warn the reader when being serious ;-) Ah, well then... ;-) Over in the land of POV-Ray, it's sort-of a tradition for your email signature to contain a tiny block of Scene Description Language source code that causes POV-Ray to render your name, or at least render something appropriate. (For those who don't know, POV-Ray is a ray tracer who's Scene Description Language is now in fact Turing-complete - although it is only a sort of macro expansion kind of beast.) Maybe I should start a new tradition where Haskellers have a blob of Haskell as their sig? (I can't *wait* to see what the luminaries such as dons, dcoutts and igloo come up with...) Ah, but a blob of code that does _what_? POV-Ray renders your name in trippy 3D, but Haskell...? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
2008/10/1 wman <[EMAIL PROTECTED]>: > > PS: Sorry, Andrew, that I first posted the reply directly to you, still > getting used to the fact that gmail kindly replies to the user on whose > behalf the message was sent, not to the list. I think that's a list setting, not a gmail one. martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
On Oct 1, 2008, at 15:51 , Andrew Coppin wrote: wman wrote: Long story short, I promised him a one-liner to "show the power and beauty of Haskell". (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $ parseCSVFromFile "input.csv") Is there room for improvement ? Um... Does anybody else find it interesting that we are "showing the beauty of Haskell" by attempting to construct the most terse, cryptic, unmaintainable tangle of point-free code that the combined mindpower of the entire mailing list can produce? To a certain geek mindset, that *is* the power and beauty. (Then again, that's the mindset that publishes incomprehensible JAPHs in their .signature files.) -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Thats why i put those quotation marks around that part of sequence ;-)) AFAIK one-liners never were about comprehensibility, just about what you can cram into one line of code. Any programmer should have no problems guessing what the line does does (even more so when looking at the "final" version without the abundant liftM's), the beauty of it lies in figuring how the heck it does what it does. And figuring that out should bring the "profound enlightenment experience; that experience which should make you a better programmer for the rest of your days, even if you never actually use Lisp -erm Haskell- itself a lot" (my apologies, P. Graham, for cannibalizing your words). I should probably get myself a signature stating that i will explicitly warn the reader when being serious ;-) PS: Sorry, Andrew, that I first posted the reply directly to you, still getting used to the fact that gmail kindly replies to the user on whose behalf the message was sent, not to the list. On Wed, Oct 1, 2008 at 9:51 PM, Andrew Coppin <[EMAIL PROTECTED]>wrote: > wman wrote: > >> Long story short, I promised him a one-liner to "show the power and beauty >> of Haskell". >> >> (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $ >> parseCSVFromFile "input.csv") >> >> Is there room for improvement ? >> > > Um... Does anybody else find it interesting that we are "showing the beauty > of Haskell" by attempting to construct the most terse, cryptic, > unmaintainable tangle of point-free code that the combined mindpower of the > entire mailing list can produce? > > Yes, there is much to be said for the power and brevity of Haskell. But you > *can* go over the top here, people! o_O > > Keep it short _yet comprehensible_, IMHO. > > > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
wman wrote: Long story short, I promised him a one-liner to "show the power and beauty of Haskell". (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $ parseCSVFromFile "input.csv") Is there room for improvement ? Um... Does anybody else find it interesting that we are "showing the beauty of Haskell" by attempting to construct the most terse, cryptic, unmaintainable tangle of point-free code that the combined mindpower of the entire mailing list can produce? Yes, there is much to be said for the power and brevity of Haskell. But you *can* go over the top here, people! o_O Keep it short _yet comprehensible_, IMHO. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
On Wed, 2008-10-01 at 10:15 +0200, Ketil Malde wrote: > Derek Elkins <[EMAIL PROTECTED]> writes: > > >> parseCSVFromFile "in.csv" >>= return . either (const "error!") > > > Whenever you see this >>= return . f pattern think liftM or fmap or <$>. > > ...and "return . f >>= action" is just "action . f", no? Well actually that's \x -> action (return (f x)) x via the (r ->) instance of Monad. I think what you wanted was \x -> return (f x) >>= action which is \x -> action (f x) action . f via the monad laws. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Derek Elkins <[EMAIL PROTECTED]> writes: >> parseCSVFromFile "in.csv" >>= return . either (const "error!") > Whenever you see this >>= return . f pattern think liftM or fmap or <$>. ...and "return . f >>= action" is just "action . f", no? -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
On Tue, 2008-09-30 at 14:54 -0400, Graham Fawcett wrote:
> 2008/9/30 wman <[EMAIL PROTECTED]>:
> > I got asked how to do one particular thing in excel, which led to discssion
> > with "our local MSOffice expert".
> > During the discussion I stated that's it too much of a PITA and that I'd
> > rather write a script.
> > Long story short, I promised him a one-liner to "show the power and beauty
> > of Haskell".
> >
> > I got the csv package from hackage, modified the parseCSVFromFile so it's
> > returns IO CSV rather than IO (Either ParseError CSV), and finished with
> > following code
> >
> > (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
> > parseCSVFromFile "input.csv")
> >
> > Is there room for improvement ?
> > Could it still be made into one-liner without modifying the csv module (and
> > without resorting to
> > case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
> > kind of tricks) ?
>
> How about:
>
> parseCSVFromFile "in.csv" >>= return . either (const "error!")
Whenever you see this >>= return . f pattern think liftM or fmap or <$>.
> printCSV >>= writeFile "out.csv"
(either (const "error!") printCSV <$> parseCSVFromFile "in.csv") >>=
writeFile "out.csv"
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Re: [Haskell-cafe] csv one-liner
On Tue, 30 Sep 2008, wman wrote: Thanks a lot, I've had a hunch it was possible to get rid of those those liftM's. I turned it into: (writeFile "output.csv") . printCSV . (map updateLine) . (either (error "Chyba pri cteni CSV.") id) =<< parseCSVFromFile "input.csv" You may even remove parentheses around 'writeFile', 'map' and 'either'. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
True, true. And i told myself no-one would notice ;-)) On Tue, Sep 30, 2008 at 9:51 PM, Graham Fawcett <[EMAIL PROTECTED]>wrote: > 2008/9/30 wman <[EMAIL PROTECTED]>: > > Thanks a lot, I've had a hunch it was possible to get rid of those those > > liftM's. I turned it into: > > > > (writeFile "output.csv") . printCSV . (map updateLine) . (either (error > > "Chyba pri cteni CSV.") id) =<< parseCSVFromFile "input.csv" > > > > and am sincerely hoping he will try to decypher it's meaning ;-))) > > It looks like you've added some good error-czeching code here. :-; > > G > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
2008/9/30 wman <[EMAIL PROTECTED]>: > Thanks a lot, I've had a hunch it was possible to get rid of those those > liftM's. I turned it into: > > (writeFile "output.csv") . printCSV . (map updateLine) . (either (error > "Chyba pri cteni CSV.") id) =<< parseCSVFromFile "input.csv" > > and am sincerely hoping he will try to decypher it's meaning ;-))) It looks like you've added some good error-czeching code here. :-; G ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Thanks a lot, I've had a hunch it was possible to get rid of those those liftM's. I turned it into: (writeFile "output.csv") . printCSV . (map updateLine) . (either (error "Chyba pri cteni CSV.") id) =<< parseCSVFromFile "input.csv" and am sincerely hoping he will try to decypher it's meaning ;-))) On Tue, Sep 30, 2008 at 9:01 PM, Simon Brenner <[EMAIL PROTECTED]> wrote: > Something like this perhaps: > > writeFile "output.csv" . printCSV . map updateLine . fromRight =<< > parseCSVFromFile "input.csv" > > (with fromRight = either (error "fromRight :: Left") id or something > equivalent) > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] csv one-liner
Something like this perhaps:
writeFile "output.csv" . printCSV . map updateLine . fromRight =<<
parseCSVFromFile "input.csv"
(with fromRight = either (error "fromRight :: Left") id or something equivalent)
On 9/30/08, wman <[EMAIL PROTECTED]> wrote:
> I got asked how to do one particular thing in excel, which led to discssion
> with "our local MSOffice expert".
> During the discussion I stated that's it too much of a PITA and that I'd
> rather write a script.
> Long story short, I promised him a one-liner to "show the power and beauty
> of Haskell".
>
> I got the csv package from hackage, modified the parseCSVFromFile so it's
> returns IO CSV rather than IO (Either ParseError CSV), and finished with
> following code
>
> (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
> parseCSVFromFile "input.csv")
>
> Is there room for improvement ?
> Could it still be made into one-liner without modifying the csv module (and
> without resorting to
> case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
> kind of tricks) ?
>
>
> Thanks, wman.
>
> ___
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> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>
>
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Re: [Haskell-cafe] csv one-liner
2008/9/30 wman <[EMAIL PROTECTED]>:
> I got asked how to do one particular thing in excel, which led to discssion
> with "our local MSOffice expert".
> During the discussion I stated that's it too much of a PITA and that I'd
> rather write a script.
> Long story short, I promised him a one-liner to "show the power and beauty
> of Haskell".
>
> I got the csv package from hackage, modified the parseCSVFromFile so it's
> returns IO CSV rather than IO (Either ParseError CSV), and finished with
> following code
>
> (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
> parseCSVFromFile "input.csv")
>
> Is there room for improvement ?
> Could it still be made into one-liner without modifying the csv module (and
> without resorting to
> case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
> kind of tricks) ?
>
I have good news for you:
either :: (b ->c) (a -> c) (Either b a) -> c
That type signature is from memory, but you get the idea. You pass in
two functions - one to deal with the Left and the other to deal with
the Right, and it sorts out your result for you.
Cheers,
D
--
Dougal Stanton
[EMAIL PROTECTED] // http://www.dougalstanton.net
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Re: [Haskell-cafe] csv one-liner
2008/9/30 wman <[EMAIL PROTECTED]>:
> I got asked how to do one particular thing in excel, which led to discssion
> with "our local MSOffice expert".
> During the discussion I stated that's it too much of a PITA and that I'd
> rather write a script.
> Long story short, I promised him a one-liner to "show the power and beauty
> of Haskell".
>
> I got the csv package from hackage, modified the parseCSVFromFile so it's
> returns IO CSV rather than IO (Either ParseError CSV), and finished with
> following code
>
> (writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
> parseCSVFromFile "input.csv")
>
> Is there room for improvement ?
> Could it still be made into one-liner without modifying the csv module (and
> without resorting to
> case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
> kind of tricks) ?
How about:
parseCSVFromFile "in.csv" >>= return . either (const "error!")
printCSV >>= writeFile "out.csv"
using Data.Either (either) ?
Graham
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Re: [Haskell-cafe] csv one-liner
On Tue, 30 Sep 2008, wman wrote:
I got asked how to do one particular thing in excel, which led to discssion
with "our local MSOffice expert".
During the discussion I stated that's it too much of a PITA and that I'd
rather write a script.
Long story short, I promised him a one-liner to "show the power and beauty
of Haskell".
I got the csv package from hackage, modified the parseCSVFromFile so it's
returns IO CSV rather than IO (Either ParseError CSV), and finished with
following code
(writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
parseCSVFromFile "input.csv")
Is there room for improvement ?
Could it still be made into one-liner without modifying the csv module (and
without resorting to
case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
kind of tricks) ?
The line will become a little longer, but you can wrap IO (Either ...) in
an ErrorT, use its exception handling capability and unwrap the complete
action. Or you replace 'case' on Either by 'either (const []) id' or
'either (error "could not open file") id'.
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[Haskell-cafe] csv one-liner
I got asked how to do one particular thing in excel, which led to discssion
with "our local MSOffice expert".
During the discussion I stated that's it too much of a PITA and that I'd
rather write a script.
Long story short, I promised him a one-liner to "show the power and beauty
of Haskell".
I got the csv package from hackage, modified the parseCSVFromFile so it's
returns IO CSV rather than IO (Either ParseError CSV), and finished with
following code
(writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $
parseCSVFromFile "input.csv")
Is there room for improvement ?
Could it still be made into one-liner without modifying the csv module (and
without resorting to
case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x}
kind of tricks) ?
Thanks, wman.
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