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You can reach the person managing the list at beginners-ow...@haskell.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Beginners digest..." Today's Topics: 1. Re: on (Erlend Hamberg) 2. Re: on (Ivan Uemlianin) 3. Re: High precision doubles (Rafael Gustavo da Cunha Pereira Pinto) 4. Re: if True than let... (Heinrich Apfelmus) 5. Re: Re: if True than let... (Andrew Wagner) 6. Gtk2Hs and Cairo on Windows (Philippe D.-P.) 7. Re: Gtk2Hs and Cairo on Windows (Maur??cio) 8. Re: [Haskell-cafe] What is an "expected type" ... (Joe Fredette) ---------------------------------------------------------------------- Message: 1 Date: Fri, 26 Jun 2009 11:24:24 +0200 From: Erlend Hamberg <ehamb...@gmail.com> Subject: Re: [Haskell-beginners] on To: beginners@haskell.org Message-ID: <ac30b3780906260224r34b3bb4arb0b30a4a7eb93...@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 2009/6/26 Ivan Uemlianin <i...@llaisdy.com>: > My question is: what is "on"? > I'm afraid I haven't been able to find anything about this, no doubt because > of all the false positives coming up in searches. http://www.haskell.org/hoogle/?hoogle=on -- Erlend Hamberg ehamb...@gmail.com ------------------------------ Message: 2 Date: Fri, 26 Jun 2009 10:27:47 +0100 From: Ivan Uemlianin <i...@llaisdy.com> Subject: Re: [Haskell-beginners] on To: beginners@haskell.org Message-ID: <4a449493.5000...@llaisdy.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Erlend Hamberg wrote: > 2009/6/26 Ivan Uemlianin <i...@llaisdy.com>: > >> My question is: what is "on"? >> I'm afraid I haven't been able to find anything about this, no doubt because >> of all the false positives coming up in searches. >> > > http://www.haskell.org/hoogle/?hoogle=on > Wow that was fast! Thanks, I hadn't tried Hoogle before and what I needed was the top hit: http://haskell.org/ghc/docs/latest/html/libraries/base/Data-Function.html#v%3Aon Ivan -- ============================================================ Ivan A. Uemlianin Speech Technology Research and Development i...@llaisdy.com www.llaisdy.com llaisdy.wordpress.com www.linkedin.com/in/ivanuemlianin "Froh, froh! Wie seine Sonnen, seine Sonnen fliegen" (Schiller, Beethoven) ============================================================ ------------------------------ Message: 3 Date: Fri, 26 Jun 2009 07:52:03 -0300 From: Rafael Gustavo da Cunha Pereira Pinto <rafaelgcpp.li...@gmail.com> Subject: Re: [Haskell-beginners] High precision doubles To: beginners@haskell.org Message-ID: <351ff25e0906260352u3d84de0auc5d48a4825890...@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Point noted, it doesn't seem to be the case for the original question, as he is doing some square roots. On Fri, Jun 26, 2009 at 04:00, <a...@spamcop.net> wrote: > G'day all. > > Quoting Rafael Gustavo da Cunha Pereira Pinto <rafaelgcpp.li...@gmail.com > >: > > I am reading this and still don't understand what is the question. You >> should never operate two floating point numbers expecting to result zero. >> Period. >> > > WARNING: Advanced material follows. > > A 32-bit integer fits losslessly in the mantissa of a Double. Any of > the basic integer operations which work correctly on 32-bit integers > must also work correctly when that integer is stored in a Double. You > are allowed to assume this. > > Cheers, > Andrew Bromage > > _______________________________________________ > Beginners mailing list > Beginners@haskell.org > http://www.haskell.org/mailman/listinfo/beginners > -- Rafael Gustavo da Cunha Pereira Pinto Electronic Engineer, MSc. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.haskell.org/pipermail/beginners/attachments/20090626/7ab78cc4/attachment-0001.html ------------------------------ Message: 4 Date: Fri, 26 Jun 2009 13:30:22 +0200 From: Heinrich Apfelmus <apfel...@quantentunnel.de> Subject: [Haskell-beginners] Re: if True than let... To: beginners@haskell.org Message-ID: <h22bgb$34...@ger.gmane.org> Content-Type: text/plain; charset=ISO-8859-1 Andrew Wagner wrote: > Try this: let b = if a == True then "+" else "-" in ... The little figurine of Dijkstra in my head is urging me to write this as let b = if a then "+" else "-" in ... instead. ;) Regards, apfelmus -- http://apfelmus.nfshost.com ------------------------------ Message: 5 Date: Fri, 26 Jun 2009 08:50:40 -0400 From: Andrew Wagner <wagner.and...@gmail.com> Subject: Re: [Haskell-beginners] Re: if True than let... To: Heinrich Apfelmus <apfel...@quantentunnel.de> Cc: beginners@haskell.org Message-ID: <b8a8636e0906260550x719f31c0x3275b19698851...@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Well sure. I was assuming it was a simplified example... On Fri, Jun 26, 2009 at 7:30 AM, Heinrich Apfelmus < apfel...@quantentunnel.de> wrote: > Andrew Wagner wrote: > > Try this: let b = if a == True then "+" else "-" in ... > > The little figurine of Dijkstra in my head is urging me to write this as > > let b = if a then "+" else "-" in ... > > instead. ;) > > > Regards, > apfelmus > > -- > http://apfelmus.nfshost.com > > _______________________________________________ > Beginners mailing list > Beginners@haskell.org > http://www.haskell.org/mailman/listinfo/beginners > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.haskell.org/pipermail/beginners/attachments/20090626/5e73562a/attachment-0001.html ------------------------------ Message: 6 Date: Fri, 26 Jun 2009 21:51:53 -0400 From: "Philippe D.-P." <shinka.suug...@gmail.com> Subject: [Haskell-beginners] Gtk2Hs and Cairo on Windows To: beginners@haskell.org Message-ID: <a1f5846a0906261851x209920berabff4220a552a...@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Hello, I would like to use Haskell with Gtk2Hs/Cairo for a project, but I have trouble making it work on Windows. I've installed the lastest GHC + Gtk2Hs and I tried to copy/paste the code from examples on this tutorial http://darcs.haskell.org/gtk2hs/docs/tutorial/Tutorial_Port/app1.xhtml. On linux; no problem. But for some reason I get a "not in scope: `eventSent`" error on Windows and I can't compile. How can I solve the problem and, more importantly, is it possible to write portable code with Gtk2Hs/Cairo ? Thank you -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.haskell.org/pipermail/beginners/attachments/20090626/198c8880/attachment-0001.html ------------------------------ Message: 7 Date: Fri, 26 Jun 2009 23:40:56 -0300 From: Maur??cio <briqueabra...@yahoo.com> Subject: [Haskell-beginners] Re: Gtk2Hs and Cairo on Windows To: beginners@haskell.org Message-ID: <h240rp$eo...@ger.gmane.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed > tutorial > http://darcs.haskell.org/gtk2hs/docs/tutorial/Tutorial_Port/app1.xhtml. > On linux; no problem. > But for some reason I get a "not in scope: `eventSent`" error on Windows > and I can't compile. This tutorial is not updated to the last version of gtk2hs, or, better, it doesn't use the new names for widget events and doesn't handle then using EventM. ('onExpose', for instance, is deprecated in current gtk2hs.) I guess you installed the latest version in Windows, and that's why you have an error, since eventSent is something different in version 0.10. Your linux install is probably not the latest gtk2hs. > How can I solve the problem and, more importantly, is it possible to > write portable code with Gtk2Hs/Cairo ? Develop your applications in the latest version for all platforms. Try to install gtk2hs as user if you want, by downloading gtk2hs source code and using: ./configure --prefix=/home/mauricio --with-user-pkgconf I never had problems running the same application in linux and windows, but I can't say there's no specific functionality where problems can arrive. Cairo never gave me any problem. Best, MaurĂcio ------------------------------ Message: 8 Date: Sun, 28 Jun 2009 11:29:10 -0400 From: Joe Fredette <jfred...@gmail.com> Subject: [Haskell-beginners] Re: [Haskell-cafe] What is an "expected type" ... To: michael rice <nowg...@yahoo.com> Cc: beginners@haskell.org, Haskell Cafe mailing list <haskell-c...@haskell.org> Message-ID: <4a478c46.5050...@gmail.com> Content-Type: text/plain; charset="iso-8859-1" When Haskell runs it's type checker, it tries to "guess" the type of each function. Thats why you can write: map (+1) and it knows that you're talking about a function of type: Num a => [a] -> [a] Another thing, called 'defaulting' resolves this, but you didn't ask about that, so I won't go into it. An expected type is one that you provide to the compiler in the form of a type signature, this can be used to specialize a general type (like the one I showed) or to resolve ambiguous types the compiler can't, or just for documentation/good practice. So when I write: foo :: Num a => [a] -> [a] foo ls = map (+1) ls The "expected type" for `foo` is `Num a => [a] -> [a]`. I imagine you're asking this because you got an error which said your expected type doesn't match your inferred type. That might, for instance, happen if I wrote: bar :: String bar = 'a' 'a' has type `Char`, since `String` is not `Char`, the type checker infers that 'a' has type char, but _expects_ it to be type String. Two solutions are as follows: --- Method 1 bar :: Char bar = 'a' --- Method 2 bar :: String bar = "a" Can you see why those two changes fix the problem? Also, just as a matter of process, I forwarded this to the haskell-beginners list, as I imagine type errors like these come up a lot, and someone probably has a better explanation over there. /Joe michael rice wrote: > as opposed to an "inferred type"? > > Michael > > > ------------------------------------------------------------------------ > > _______________________________________________ > Haskell-Cafe mailing list > haskell-c...@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -------------- next part -------------- A non-text attachment was scrubbed... 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