- Haskell-Cafe - Haskell.org

Hiring and porting
by Mark Carroll 13 Mar '02

13 Mar '02

Thanks, everyone, for your responses! It's all been very helpful. Some things I should mention, then: We're based in central Ohio, but are not currently hiring FPers. Whether we will be in the future depends somewhat on this porting issue. However, if we do decide to hire any Haskell programmers, I shall mention that here. Ideally, yes, we'd look to hire practising programmers who already know Haskell and wish that they could be using it in their job, although I'd fear that there may not be enough such people available to us. The larger application is a simulation engine that involves parsing, symbolic processing, etc. in which correctness in important and that will require ongoing improvement and modification, so I was thinking that use of Haskell would be appropriate. (Use of C++ would make it faster, though, I expect. (-:) However, I do fear that Ashley's correct in suggesting that you'd probably need to rewrite everything to sensibly translate the Haskell to C or Java or whatever, and it is both reasonable and plausible that some larger clients will demand use of a more mainstream language in anything that we deliver to them so that they don't rely on us for maintenance. So, first we have to figure out if we should use Haskell at all, because a likely need for a non-trivial port in the future could easily negate, in time and cost, the initial productivity benefits we might gain from Haskell. -- Mark

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Re: IO and syntax
by Ashley Yakeley 13 Mar '02

13 Mar '02

At 2002-03-12 20:18, Jyrinx wrote: >Of course, this "probable cause" is ridiculous at face value ... anyway, >my code makes as much sense to me as it can at the moment ... how should >I get it to make sense to GHC? (I couldn't find any examples on I can see the bug. It's a very common one when using monads and the 'do' notation -- confusing 'a' with 'IO a'. When in doubt, add type signatures to everything. You'll soon narrow it down. -- Ashley Yakeley, Seattle WA

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IO and syntax
by Jyrinx 13 Mar '02

13 Mar '02

I just got back from a high-school programming competition where the only allowed languages were C[++] and Java (*grmbl*). To see just how cool Haskell is, I'm redoing some of the problems in this more enlightened language :-) Anyway, that explains the rather strict requirements for my program's interface. At one point, the user must enter pairs of numbers like so: 1 4 2 4 3 2 4 1 4 3 0 0 (where two zeros terminate the input). Here is my latest attempt at a function to do this part of the problem (and it's the easy part ...) --- snip --- -- type Player = Int readIncompatList :: IO [(Player, Player)] readIncompatList = readIL' [] where readIL' ans = do a <- readDec b <- readDec if a == 0 && b == 0 then ans else readIL' ((a, b):ans) --- snip --- GHC complains with the following: --- snip --- prob13.hs:37: Couldn't match `String -> t' against `[t1]' Expected type: String -> t Inferred type: [t1] Probable cause: `(:)' is applied to too many arguments in the call ((:) (a, b) ans) In the first argument of `readIL'', namely `((a, b) : ans)' --- snip --- Of course, this "probable cause" is ridiculous at face value ... anyway, my code makes as much sense to me as it can at the moment ... how should I get it to make sense to GHC? (I couldn't find any examples on something as mundane as console I/O; funny how people are so fixated on the real stuff :-) ) Thanks! Jyrinx jyrinx_list(a)mindspring.com

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by Christine Hall 12 Mar '02

12 Mar '02

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RE: Hiring Haskell programmers
by Konst Sushenko 12 Mar '02

12 Mar '02

I have always been wondering what exactly does "quickly learn Haskell" mean? Quickly learn Haskell syntax? Can one learn how to paint quickly? konst > -----Original Message----- > From: Eray Ozkural [mailto:erayo@cs.bilkent.edu.tr] > Sent: Monday, March 11, 2002 4:24 PM > To: Mark Carroll; haskell-cafe(a)haskell.org > Subject: Re: Hiring Haskell programmers > > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Tuesday 12 March 2002 01:17, Mark Carroll wrote: > > How easy is it to hire reasonable Haskell programmers? Of > course, this may > > mean, hiring people with the aptitude and interest to quickly learn > > Haskell. Has anyone any experience of this that they can share? > > > > I know it's easy. Try me. ;) > > Sincerely, > > - -- > Eray Ozkural (exa) <erayo(a)cs.bilkent.edu.tr> > Comp. Sci. Dept., Bilkent University, Ankara > www: http://www.cs.bilkent.edu.tr/~erayo > GPG public key fingerprint: 360C 852F 88B0 A745 F31B EA0F > 7C07 AE16 874D 539C > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.0.6 (GNU/Linux) > Comment: For info see http://www.gnupg.org > > iD8DBQE8jUqcfAeuFodNU5wRAt1/AKCaN881FMXqzpx+xh1EpnFa/b6k9ACeNuPX > aYrkL3CfiF2C6uBzH+3chPs= > =U7Xm > -----END PGP SIGNATURE----- > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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RE: Hiring Haskell programmers
by Ashley Yakeley 12 Mar '02

12 Mar '02

At 2002-03-11 17:05, Mark Carroll wrote: >When I first learned Standard ML, after years of imperative >programming, my brain almost hurt for the first few weeks. For me the difference is that in imperative you tell the computer what to do, whereas in FP you tell the computer what things are. -- Ashley Yakeley, Seattle WA

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Conversion/porting to "mainstream" languages
by Mark Carroll 12 Mar '02

12 Mar '02

One criticism I've received of the suggestion that we use Haskell in our business is that some particularly large clients will demand code in some 'standard' language that they know they can deal with, especially if they end up stuck with the software and we stop supporting it. How are others dealing with this? How big a project would it be to translate, say, from Haskell to C or Java? I'm guessing that you'd borrow a lot of the type-inferencing, etc. from the current compilers - how easy is their code to get to grips with? I suppose that at least something to translate Haskell to Java bytecode would be useful someday, and then you could 'decompile' back to Java, perhaps, but as we wouldn't be doing graphical stuff with Haskell anyway then C might be best. Anyhow, any thoughts or comments on this difficulty would be of interest. -- Mark

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Re: Conversion/porting to "mainstream" languages
by Ashley Yakeley 12 Mar '02

12 Mar '02

At 2002-03-11 15:16, Mark Carroll wrote: >One criticism I've received of the suggestion that we use Haskell in our >business is that some particularly large clients will demand code in some >'standard' language that they know they can deal with, especially if they >end up stuck with the software and we stop supporting it. That's very reasonable, actually. >How are others dealing with this? How big a project would it be to >translate, say, from Haskell to C or Java? Huge. IMO, you'd probably need to rewrite everything. On the plus side, Haskell is typically excellent for exploring any problem domain. So you might end up with better designed and more maintainable Java or C code than you would if you started from scratch. Or not. -- Ashley Yakeley, Seattle WA

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Re: Hiring Haskell programmers
by Ashley Yakeley 12 Mar '02

12 Mar '02

At 2002-03-11 15:17, Mark Carroll wrote: >How easy is it to hire reasonable Haskell programmers? If you're in the Seattle area, there's this one... >Of course, this may >mean, hiring people with the aptitude and interest to quickly learn >Haskell. My best guess is if they already know ML or some other FP language, learning Haskell should not be hard. Otherwise I really don't think you can learn Haskell all that quickly. Mind you, I don't think there are all that many ML programmers out there either. -- Ashley Yakeley, Seattle WA

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informacion
by ceci 11 Mar '02

11 Mar '02

Soy estudiande universitaria de la Universidad Nacional de Cordoba ( Argentina) estoy haciendo la carrera Licenciatura en Ciencias de la Computaciòn y en una de las materias (Introducciòn a los Algoritmos) nos dieron como bibliografia para poder consultar su pagina. Yo quisiera saber como puedo conseguir su libro, asi lo puedo tener para poder estudiar Desde ya muchas gracias. Saluda muy atte. Ma.Lorena Soto

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