RE: [Haskell-cafe] Somewhat random history question
| It's interesting that the article completely fails to mention hbc | which I know they used during the GHC bootstrap. Oh well. :) | | On Nov 11, 2007 2:41 PM, Richard Kelsall [EMAIL PROTECTED] wrote: | Andrew Coppin wrote: | ...if GHC is written in Haskell, how the heck did they compile GHC in | the first place? Lennart, I'm sure this is my fault, and I do apologise. If we used hbc in the bootstrap, I'd completely forgotten; I thought we'd just used the LML compiler, which is indeed credited. (Perhaps not everyone knows that you wrote the LML compiler too, with Thomas Johnsson, of course. It completely changed the landscape of lazy-functional-language compilers.) What I do remember is that we constantly compared ghc's performance to hbc's, and took ages to catch up! I wish we'd corrected any errors of fact before the paper was published. (It was on the Web for 6 months before publication to accumulate corrections, but errors and omissions remain our fault.) Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Upgrading X11
On Sun, 2007-11-11 at 12:44 -0500, Brent Yorgey wrote: I think you need to run autoconf autoheader (or autoreconf) first, before running Setup configure? I could be confused, but see if that helps. If that's what the problem is, the documentation definitely needs updating. -Brent Thanks Brent, autoconf autoheader fixed it. I won't volunteer to look at the docs because I have no idea why! Jim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Somewhat random history question - chicken and egg
On Sun, 11 Nov 2007, [EMAIL PROTECTED] wrote: To be a true COBOL replacement, I think that one very important feature is that it is link-compatible with existing COBOL code. You're never going to be able to replace a 6MLOC COBOL monster in any manner other than piecemeal. AFAIK people are replacing code by writing other applications that manipulate the same data as the legacy code but do not link with it. I should ask my wife more about the structure of Peoplesoft. I know it's a mixture of COBOL, PL/SQL, and Peoplecode on the server, and Java on the client... No Haskell in it, though. Tony. -- f.a.n.finch [EMAIL PROTECTED] http://dotat.at/ WEST FAIR ISLE FAEROES SOUTHEAST ICELAND: SOUTHERLY VEERING NORTHWESTERLY 5 TO 7, OCCASIONALLY GALE 8 IN FAEROES AND SOUTHEAST ICELAND. ROUGH OR VERY ROUGH. RAIN OR SHOWERS. MODERATE OR GOOD. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] GHC6.8.1 can not compile the simple example
Hi David, In future, please post emails to haskell-cafe@, the haskell@ list is for annoucements. The correct command line is: ghc --make c.hs Thanks Neil On Nov 12, 2007 1:11 PM, david yu [EMAIL PROTECTED] wrote: Link error is: [EMAIL PROTECTED] test]$ ghc c.hs c.o: In function `rM7_info': (.text+0xaa): undefined reference to `containerszm0zi1zi0zi0_DataziMap_lookup_closure' c.o: In function `rMd_info': (.text+0x1fa): undefined reference to `containerszm0zi1zi0zi0_DataziMap_fromList_closure' c.o: In function `sVJ_info': (.text+0xa3b): undefined reference to `__stginit_containerszm0zi1zi0zi0_DataziMap_' c.o: In function `rM7_srt': (.data+0x18): undefined reference to `containerszm0zi1zi0zi0_DataziMap_lookup_closure' c.o: In function `rMd_srt': (.data+0x60): undefined reference to `containerszm0zi1zi0zi0_DataziMap_fromList_closure' collect2: ld returned 1 exit status ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell and html input elements
Hi back again! How easy/hard is it to control a haskell program through a web browser? Cheers Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and html input elements
On Nov 12, 2007, at 8:38 AM, PR Stanley wrote: Hi back again! How easy/hard is it to control a haskell program through a web browser? Hi, It depends on exactly how you want to control it, but at least some control is fairly easy. If you simply want to start a batch Haskell program, and see its output as HTML in a browser, you can use the cgi [1] or fastcgi [2] libraries listed on Hackage. If you want slightly more interactivity, it would make sense to write your Haskell program as its own web server (which is actually surprisingly easy) and have it respond to sequences of requests, perhaphs storing intermediate state along the way. Giving something like this a nice GUI on the user side will probably involve writing a certain amount of JavaScript. One example of a program that works this way is HERA [3], which is unfortunately not open-source at the moment, but may be some day. Another potentially useful library is HAppS [4], which abstracts out some of the functionality necessary for web-based applications. Is this sort of thing along the right track, or were you thinking of something else? Aaron [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ cgi-3001.1.5.1 [2] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ fastcgi-3001.0.1 [3] http://haskell.org/haskellwiki/ Haskell_Equational_Reasoning_Assistant [4] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ HAppS-0.8.4 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and html input elements
Hi If you simply want to start a batch Haskell program, and see its output as HTML in a browser, you can use the cgi [1] or fastcgi [2] libraries listed on Hackage. This is the approach that Hoogle takes, and turned out to be very easy. The code is all available, so you can start from that. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: some links broken in 6.8.1 documentation
Hello Ian 2007/11/10, Ian Lynagh [EMAIL PROTECTED]: Hi Daniil, On Sun, Nov 04, 2007 at 03:49:54PM +0300, Daniil Elovkov wrote: A quick look at the 6.8.1 user's guide reveals some broken links: 1) Obtaining code coverage, pointing to http://haskell.org/ghc/docs/6.8.1/html/users_guide/hpc.html redirects to http://projects.unsafeperformio.com/hpc.html which tells that it's not found but guesses at another location, where it is found. I can't see any link to http://projects.unsafeperformio.com/hpc.html in the users guide - am I missing something? Oops. I don't know what it was but it's definitely alright now. 2) Concurrent and parallel haskell http://haskell.org/ghc/docs/6.8.1/html/users_guide/lang-parallel.html (and possibly other pages) have links to libraries according to the pre-base-split structure, like .../base/.. instead of .../parallel/..., which results in those links being broken. Thanks; I've filed a bug here: http://hackage.haskell.org/trac/ghc/ticket/1864 Indeed, version numbers are also in the way. The easy part of the problem is that pages in the user's guide also link to base where they should link to new packages emerged from base, like parallel. As for version numbers, I'd like to make it more clear to me, what the split will lead to. Do I understand it right that the idea of the split was letting all packages (possibly apart from base) emerge more or less independently from ghc releases? So, can package version numbers increase under the same 6.8.1 directory over time? And, if a package is updated between two ghc releases, will the extralibs tarball be updated (and precompiled binary ghc packages, for that matter) ? -- Daniil Elovkov ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: some links broken in 6.8.1 documentation
Hello Daniil, Monday, November 12, 2007, 7:56:23 PM, you wrote: And, if a package is updated between two ghc releases, will the extralibs tarball be updated (and precompiled binary ghc packages, for that matter) ? i think it will be bad idea. instead, anyone who need to have latest package, should install 6.8.1 plus any updated libraries -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Why are OCaml and Haskell being used at these companies?
Hello, Using http://www.indeed.com with the search phrase Haskell functional, I found several Haskell positions inclusing Quantitative Functional Programmer (Analyst - Level)http://www.indeed.com/rc/clk?jk=950afd03471e43cbfrom=jacd=0B84_stXHsQIi--kqgcAtwkqfEFNHwdDbrS1x6sG6qd6vVd2F9lWGMmpcNKZhUl4vYoq6CxBPHbov0Iq1E7i0I280wysegJY2TsQ1uFW7W_5TT4m0Zj94dTxgyQTopT3S0sT8XXLFkgUNtb7Vnd-g90KjCOBR8L3-j4DDe5C5IWB90L0VOIkMXvl8vqDEnzncPVLYuVLwWSceCP4ZHmZ3460UPeMcjpKVyHhxzB4j1RctniY18yLwC5uX2r9d7cvhgE9HBp5fU9Mwl9IHrzlc5G6Snh7h8t7rIdr7Jgu3cEqd=RnZhMybXSk4M3QtTVGXWoYOKTPFCbzpm8jWESW0p0eMKASM0UIjh16lawXYVmI3Pl-Bs_tBXR8fwdr6b7g8zZmd1JbykUrZLXGO6H03JYDQrd=i9i5wxAjTH4MK5Gz0qo8FA Credit Suisse - New York, NY Specific *Language* (embedded in *Haskell*) that will be... of competence in either *Haskell* or another statically-typed functional *language*. The ability to build... From Credit Suisse - November 11, 3:32 PM I am looking for (objective.. i.e. not juts FPL cheerleading) opinions as to why Wall Street ( http://www.janestcapital.com/) and banking are now using OCaml and Haskell. I really want to understand what industrial markets are adopting FPLs and why in order to help push FPLs penetration into industry. Another company is http://www.galois.com Kind regards, Vasya ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why are OCaml and Haskell being used at these companies?
vigalchin: I am looking for (objective.. i.e. not juts FPL cheerleading) opinions as to why Wall Street ( [3]http://www.janestcapital.com/) and banking are now using OCaml and Haskell. I really want to understand what industrial markets are adopting FPLs and why in order to help push FPLs penetration into industry. Another company is [4]http://www.galois.com Perhaps start at http://cufp.galois.com/. A quick summary: small differences in productivity show up as real dollar amounts to banking/wall street types, and faults are less tolerated than in some industries. Galois, in particular, is in it for the the high assurance/correctness aspects. So: * productivity * correctness -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Somewhat random history question
No worries. I read the History of Haskell paper twice, but not the final version, I guess. As far as I remember you started the bootstrapping with the ghc built on the LML compiler. But as hbc became available it was soon more reliable and produced better code, so you switched to that until the new ghc could compile itself. That's how I remember it. There's also a bunch of Prelude related code in the ghc libraries that originates with hbc. I've been to lazy to send any bug reports about this. (Just to get a line of attribution.) -- Lennart On Nov 12, 2007 9:33 AM, Simon Peyton-Jones [EMAIL PROTECTED] wrote: | It's interesting that the article completely fails to mention hbc | which I know they used during the GHC bootstrap. Oh well. :) | | On Nov 11, 2007 2:41 PM, Richard Kelsall [EMAIL PROTECTED] wrote: | Andrew Coppin wrote: | ...if GHC is written in Haskell, how the heck did they compile GHC in | the first place? Lennart, I'm sure this is my fault, and I do apologise. If we used hbc in the bootstrap, I'd completely forgotten; I thought we'd just used the LML compiler, which is indeed credited. (Perhaps not everyone knows that you wrote the LML compiler too, with Thomas Johnsson, of course. It completely changed the landscape of lazy-functional-language compilers.) What I do remember is that we constantly compared ghc's performance to hbc's, and took ages to catch up! I wish we'd corrected any errors of fact before the paper was published. (It was on the Web for 6 months before publication to accumulate corrections, but errors and omissions remain our fault.) Simon ___ 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
[Haskell-cafe] Interesting effect of upgrading GHC
Hi guys. I just removed GHC 6.6.1 and installed 6.8.1, and I noticed something rather unexpected. I recompiled an existing program (with -O2), and instead of taking 30 seconds to compile, it took roughly 2 seconds. That's a really serious speedup! o_O Anybody have any idea what might have caused this? (Not, you understand, that I'm complaining! But the release notes say 10-15% faster, not 15,000% faster...) I am also curiose to see whether the compiled code execution speed is better/worse - but the program in question is mainly GUI, so I can't test it with that... Perhaps my Chaos program? ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interesting effect of upgrading GHC
Hi I just removed GHC 6.6.1 and installed 6.8.1, and I noticed something rather unexpected. I recompiled an existing program (with -O2), and instead of taking 30 seconds to compile, it took roughly 2 seconds. In previous releases, certain constructs took O(n^2) time to compile. One that was a particular issue for me was: do return () return () return () Once you got to 100 return ()'s in a row GHC was totally useless, while Yhc and Hugs both had no problems. This particular problem was fixed, and I think a few others were as well - if one of those had tripped you up that may explain the speedup. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interesting effect of upgrading GHC
Not sure if this is the case but if you don't delete the old object files and executable GHC may think that its job is already done and give up early. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: How to do this in Haskell
Chris Smith wrote: Right, which is why I'm trying to avoid reinventing it. Writing a new HTML editor is not even a consideration. I'm looking at the effort to integrate the Mozilla editor component, and wondering if there are other components that could be used instead in a Gtk2Hs application. A not-so-well-known feature of X11 is reparenting of windows. You should be able to take any X11 app and have it display in a window of your choice inside your app. So pick an HTML editor and integrate it into your app that way. -- Joe Buehler ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Weird ghci behaviour?
Several months late I now have a simple test case for what I think is either a GHC bug or a misexpectation on my part. This is with GHC 6.8.1 and I've tested both under Linux and MacOSX. It took a while to reproduce it because I thought the problem had gone away, but actually I'd just misunderstood when it happens. Here's a transcript of a complete session with a shell to make it easy to reproduce. Note how on the second run, ghci behaves differently. -- cat bug.hs x = 1 main = do print x ghci bug.hs GHCi, version 6.8.1: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. [1 of 1] Compiling Main ( bug.hs, interpreted ) Ok, modules loaded: Main. *Main main 1 *Main x 1 *Main :q Leaving GHCi. ghc bug.hs ghci bug.hs GHCi, version 6.8.1: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. Ok, modules loaded: Main. Prelude Main main 1 Prelude Main x interactive:1:0: Not in scope: `x' Prelude Main Leaving GHCi. --- On Jul 23, 2007 10:46 AM, Dan Piponi [EMAIL PROTECTED] wrote: Ian said: Can you please give a complete testcase for the problem you're seeing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Weird ghci behaviour?
Dan Piponi wrote: Several months late I now have a simple test case for what I think is either a GHC bug or a misexpectation on my part. Here's what it looks like to me. If there is a .hi and .o file sitting around for a module, then GHCi will load it in compiled mode, and only let you access those symbols that are exported by the .hi file. If you compile a source file that has no module header, it compiles to the module Main and *only* exports the symbol main. You can fix it by adding a module header explicitly, or by deleting either the .hi or .o file. This is not new with GHC 6.8. For example, it's why I had to sneakily add a module declaration to the top of a source file when I wrote http://www.haskell.org/haskellwiki/Learn_Haskell_in_10_minutes#Function_definitions -- Chris Smith ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interesting effect of upgrading GHC
Gwern Branwen wrote: FWIW, I was actually discussing compilation with -O2 on 6.8 with Sjannssen and he told me that even with -O2 turned on, GHC now defaults to -fasm instead of -fvia-c. Ah. Yeah, that could well make a big difference... (Especially on a machine with insufficient RAM.) Also, the release notes are talking about the runtime speed of binaries, not compilation. But since GHC is compiled with GHC, you would expect a (small) speedup of GHC. (And indeed that is what the release notes specifically suggest.) Either way, I (and probably a number of other people) will go test what speed difference it actually makes to compiled code. ;-) (I've been wondering for a while now whether there's much to choose between -fasm and -fvia-c.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Weird ghci behaviour?
On Mon, 12 Nov 2007, Chris Smith wrote: Dan Piponi wrote: Several months late I now have a simple test case for what I think is either a GHC bug or a misexpectation on my part. Here's what it looks like to me. If there is a .hi and .o file sitting around for a module, then GHCi will load it in compiled mode, and only let you access those symbols that are exported by the .hi file. If you compile a source file that has no module header, it compiles to the module Main and *only* exports the symbol main. You can fix it by adding a module header explicitly, or by deleting either the .hi or .o file. See http://www.haskell.org/ghc/docs/latest/html/users_guide/interactive-evaluation.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Data.Set.member vs Data.List.elem
Hi, Is there a good reason that Data.Set uses the name member while Data.List (or the Prelude) uses the name elem, for what to me seem identical concepts. I realise that in Set's the traditional test is for membership, but it seems awfully arbitrary that one jumped one way and one jumped the other. I've just written an entire module's worth of Haskell with Set.elem, as that felt right, now I'm going back and fixing it. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Weird ghci behaviour?
On Nov 12, 2007 1:59 PM, Henning Thielemann [EMAIL PROTECTED] wrote: See http://www.haskell.org/ghc/docs/latest/html/users_guide/interactive-evaluation.html I guess the key sentence is: For technical reasons, GHCi can only support the *-form for modules which are interpreted, so compiled modules and package modules can only contribute their exports to the current scope. But it does mean the interpreter isn't referentially transparent, which is weird for a language that puts so much stress on referential transparency. -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Trouble using HDBC-postgres on Windows - can't find libpq.dll
I've compiled HDBC 1.0.1 and HDBC-postgresql-1.0.1 under Windows with a little tweaking. However, when I try to run the tests I get this error: runghc -package HDBC-postgresql runtests.hs ghc.exe: can't load .so/.DLL for: pq (addDLL: unknown error) libpq.dll is in my path, and I added the correct paths to the .cabal file when I built it. Does anyone have an idea what might be the problem? Justin p.s. I have postgres 8.2 installed if that matters. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to do this in Haskell
On Mon, 2007-11-12 at 16:16 -0500, Joe Buehler wrote: Chris Smith wrote: Right, which is why I'm trying to avoid reinventing it. Writing a new HTML editor is not even a consideration. I'm looking at the effort to integrate the Mozilla editor component, and wondering if there are other components that could be used instead in a Gtk2Hs application. A not-so-well-known feature of X11 is reparenting of windows. You should be able to take any X11 app and have it display in a window of your choice inside your app. So pick an HTML editor and integrate it into your app that way. Ah yes, that's a good point. Gtk+ and Gtk2hs support this X11 feature: http://haskell.org/gtk2hs/docs/current/Graphics-UI-Gtk-Embedding-Plug.html http://haskell.org/gtk2hs/docs/current/Graphics-UI-Gtk-Embedding-Socket.html Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Set.member vs Data.List.elem
Perhaps this has something to due with uniqueness. A list can have many duplicate elements while a set is supposed to be unique. On Nov 12, 2007 2:48 PM, Neil Mitchell [EMAIL PROTECTED] wrote: Hi, Is there a good reason that Data.Set uses the name member while Data.List (or the Prelude) uses the name elem, for what to me seem identical concepts. I realise that in Set's the traditional test is for membership, but it seems awfully arbitrary that one jumped one way and one jumped the other. I've just written an entire module's worth of Haskell with Set.elem, as that felt right, now I'm going back and fixing it. Thanks Neil ___ 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] Why are OCaml and Haskell being used at these companies?
On Nov 12, 2007, at 12:00 PM, Galchin Vasili wrote: I am looking for (objective.. i.e. not juts FPL cheerleading) opinions as to why Wall Street ( http://www.janestcapital.com/) and banking are now using OCaml and Haskell. I really want to understand what industrial markets are adopting FPLs and why in order to help push FPLs penetration into industry. I wouldn't know about that, but incidentally, the first I heard of a distinct Wall Street software world, in the 90's, they were looking for Smalltalk programmers. Who knows what those crazy guys will be doing next. Donn Cave, [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] can someone explain monad transformers to me, or how do you combine maybe and IO?
I wanted something that would work like liftM but with IO as well, so something like this: liftM ((+) 1) $ Just 1 Just 2 but with the function lifted being of type (a - IO b). so I came up with maybeIO::(a - IO b) - (Maybe a - IO (Maybe b)) maybeIO ff = (\ aa - case aa of Nothing - return $ Nothing Just vv - do rv - ff vv return $ Just rv) incIO:: Int - IO Int incIO ii = return $ ii + 1 maybeIO incIO $ Just 1 Just 2 works just like I want it to. But isn't this something that a monad transformer should be able to do? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Weird ghci behaviour?
For technical reasons, GHCi can only support the *-form for modules which are interpreted, so compiled modules and package modules can only contribute their exports to the current scope. But it does mean the interpreter isn't referentially transparent, which is weird for a language that puts so much stress on referential transparency. iirc, you can use -fforce-recomp with GHCi, to make it look for sources, ignoring compiled code, if that is what you want: http://www.haskell.org/ghc/docs/latest/html/users_guide/separate-compilation.html#recomp claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] can someone explain monad transformers to me, or how do you combine maybe and IO?
On Nov 12, 2007 11:59 PM, Anatoly Yakovenko [EMAIL PROTECTED] wrote: works just like I want it to. But isn't this something that a monad transformer should be able to do? Yes. And I have rewritten MaybeT several times for use in my own projects. We want MaybeT! Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why are OCaml and Haskell being used at these companies?
On Mon, 2007-11-12 at 15:51 -0800, Donn Cave wrote: On Nov 12, 2007, at 12:00 PM, Galchin Vasili wrote: I am looking for (objective.. i.e. not juts FPL cheerleading) opinions as to why Wall Street ( http://www.janestcapital.com/) and banking are now using OCaml and Haskell. I really want to understand what industrial markets are adopting FPLs and why in order to help push FPLs penetration into industry. I wouldn't know about that, but incidentally, the first I heard of a distinct Wall Street software world, in the 90's, they were looking for Smalltalk programmers. Who knows what those crazy guys will be doing next. Epigram? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] can someone explain monad transformers to me, or how do you combine maybe and IO?
On Nov 13, 2007 1:08 AM, Luke Palmer [EMAIL PROTECTED] wrote: We want MaybeT! I third this proposal. It would be nice having MaybeT included in mtl. Besides, and although it's not exactly the same, you can emulate the Maybe monad by using the Either monad (the instance is defined in Control.Monad.Error). And in this case you want a monad transformer, so ErrorT can do the trick. Just consider that all the Left values are Nothing and the Right values are Just. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Fwd: Trouble using HDBC-postgres on Windows - can't find libpq.dll
Well, I answered my own question. Unlike UNIX, specifying a library without the leading lib causes the library to not be found. Not sure if that's a GHC linking problem or what. Changing the library requirement to libpq in the .cabal file did the trick tho. Justin -- Forwarded message -- From: Justin Bailey [EMAIL PROTECTED] Date: Nov 12, 2007 3:41 PM Subject: Trouble using HDBC-postgres on Windows - can't find libpq.dll To: Haskell Cafe haskell-cafe@haskell.org I've compiled HDBC 1.0.1 and HDBC-postgresql-1.0.1 under Windows with a little tweaking. However, when I try to run the tests I get this error: runghc -package HDBC-postgresql runtests.hs ghc.exe: can't load .so/.DLL for: pq (addDLL: unknown error) libpq.dll is in my path, and I added the correct paths to the .cabal file when I built it. Does anyone have an idea what might be the problem? Justin p.s. I have postgres 8.2 installed if that matters. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why are OCaml and Haskell being used at these companies?
On Monday 12 November 2007 20:00, Galchin Vasili wrote: I am looking for (objective.. i.e. not juts FPL cheerleading) opinions as to why Wall Street ( http://www.janestcapital.com/) and banking are now using OCaml and Haskell. They have been using OCaml and Haskell for many years now. They were among the first industrial adopters of modern statically-typed functional programming languages along with companies like Intel and Microsoft who use them to write verification software. I really want to understand what industrial markets are adopting FPLs and why in order to help push FPLs penetration into industry. Another company is http://www.galois.com Kind regards, Vasya For the old examples that you gave, reliability was a major concern. Functional programming languages are now much more widely used in industry, primarily because they offer substantial productivity improvements (roughly 10x) over C++ and Java and, consequently, are much more cost effective. Penetration is highest in parts of industry where small groups of talented programmers get together, most notably startups. Look at XenSource, Wolfram Research, The MathWorks, Wink, Merjis, Red Hat, Linspire and Skydeck for example. -- Dr Jon D Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/products/?e ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
