Posix.getFileStatus
(1) I think Posix.getFileStatus should respond to a file which isn't there with something rather more helpful than system error. For example, a No such file or directory message. (2) The logical way of spotting whether a file is actually there is the queryFile function, documented for example here: http://haskell.cs.yale.edu/ghc/docs/latest/html/hslibs/files-and-directories.html But sadly the queryFile function does not appear to be in the Posix module! At least not for ghc5.04.2. Good thing there's a Directory.doesFileExist function! Of course that's not quite the same, since it only checks if there is a normal file of that name (it returns False for a directory). ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: Posix.getFileStatus
(1) I think Posix.getFileStatus should respond to a file which isn't there with something rather more helpful than system error. For example, a No such file or directory message. With today's CVS sources: Prelude System.Posix.getFileStatus /tmp/foo Loading package unix ... linking ... done. *** Exception: does not exist Action: getFileStatus Reason: No such file or directory The posix library is undergoing a rewrite, which is about 80-90% done so far. I'd appreciate any testing you can subject the new System.Posix library to, though. Cheers, Simon ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: Posix.getFileStatus
George Russell wrote: (2) The logical way of spotting whether a file is actually there is the queryFile function, documented for example here: http://haskell.cs.yale.edu/ghc/docs/latest/html/hslibs/files-and-directories.html But sadly the queryFile function does not appear to be in the Posix module! At least not for ghc5.04.2. Apparently, `queryAccess` and `queryFile` are called `fileAccess` and `fileExist`. Dean ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
unknown architecture bug
Any idea what would cause this: ch --make Train.hs -fglasgow-exts -osuf sun4.o -hisuf sun4.hi ghc-5.04.2: chasing modules from: Train.hs Compiling NLP.PTBDefs2 ( /nfs/isd/hdaume/projects/NLP/PTBDefs2.lhs, /nfs/isd/hdaume/projects/NLP/PTBDefs2.sun4.o ) /nfs/isd/hdaume/projects/NLP/PTBDefs2.lhs:221: Warning: Pattern match(es) are overlapped In the definition of `fixLex': fixLex (TDash : (TRP : xs)) = ... Compiling NLP.PTBParser2 ( /nfs/isd/hdaume/projects/NLP/PTBParser2.hs, /nfs/isd/hdaume/projects/NLP/PTBParser2.sun4.o ) Compiling Train( Train.hs, ./Train.sun4.o ) 8:55am moussor:Paraphrases/ touch Train.hs DING! moussor:Paraphrases/ ghci Train.hs ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 5.04.2, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \/\/ /_/\/|_| Type :? for help. Loading package base ... linking ... done. Loading package haskell98 ... linking ... done. Loading package lang ... linking ... done. Skipping NLP.PTBDefs2 ( /nfs/isd/hdaume/projects/NLP/PTBDefs2.lhs, /nfs/isd/hdaume/projects/NLP/PTBDefs2.sun4.o ) Skipping NLP.PTBParser2 ( /nfs/isd/hdaume/projects/NLP/PTBParser2.hs, /nfs/isd/hdaume/projects/NLP/PTBParser2.sun4.o ) Compiling Train( Train.hs, interpreted ) /nfs/isd/hdaume/projects/NLP/PTBDefs2.sun4.o: unknown architecture ghc-5.04.2: panic! (the `impossible' happened, GHC version 5.04.2): loadObj: failed Please report it as a compiler bug to [EMAIL PROTECTED], or http://sourceforge.net/projects/ghc/. This has happened to me a few times and by removing the offending .o file and rebuilding, everything works (sometimes). -- Hal Daume III | [EMAIL PROTECTED] Arrest this man, he talks in maths. | www.isi.edu/~hdaume ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: child process statistics
Dean Herington [EMAIL PROTECTED] writes: On Wed, 26 Feb 2003, Sigbjorn Finne wrote: wait3() or getrusage()? (Neither of which are supported by the posix library.) --sigbjorn Thanks, Sigbjorn. I drafted a Haskell wrapping of wait4(), modeled on code I found in CVS. See attached. I'd like a bit of help in two respects: 1. I found it difficult to satisfy the code requirements because I'm building the module outside the RTS build environment. Some issues: a. I don't know how to make a .hsc file, which would be the appropriate form for the file, I think. This meant I couldn't use #const, and may also explain why I couldn't find the __hsunix_* routines. The HsUnix.h contain these helper routines, which you'll find in the include/ subdir of the unix package. c. I'm not sure how to define `struct timeval` and `struct rusage` so I can avoid the kludgy code in `makeProcessResourceUsage`. hsc2hs does let you access fields of a struct without having to know offsets nor struct sizes (cf. getProcessTimes in Process.hsc) It seems that maybe I should be building in the RTS environment (and maybe even extending the System.Posix.Process module itself) to clean up all of the above problems. That seems a bit daunting to me, however. That makes good sense. If you're over the hurdle of setting up and building the fptools tree, there's really not much to it. Modify libraries/unix/System/Posix/Process.hsc followed by a 'make' in libraries/unix. It uses the in-tree version of hsc2hs, so you don't have to worry about setting it up. 2. Having gotten my module to compile cleanly, it--not surprisingly--fails at runtime: invalid argument Action: reapChildProcess Reason: Invalid argument I can't see anything obviously wrong with the parameters, I'm assuming the pid and the options settings are correct. Tracing the system calls will probably give you some useful info. --sigbjorn ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: fundeps known beforehand (was RE: fundeps for extended Monad definition)
| since this claims that it will take a Bool and produce a value of type b | for all types b. However, would it be all right to say (in | pseudo-Haskell): | | f :: exists b . Bool - b | f x = x But this is a singularly useless function, because it produces a result of utterly unknown type, so you can't actually use it. For example you could not say f x + 4 Simon ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Happy Alex
I have successfully used the the excellent haskell tools Happy and Alex in a couple of parsing projects, but I have failed when trying to combine a monadic Happy grammar (using the %monad and %lexer directives) together with an Alex generated okenizer, nor are there any such examples in the Happy and Alex distributions. Have anyone tried this combination and can give me some advice or a simple example? -- Per ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
RE: Happy Alex
I have successfully used the the excellent haskell tools Happy and Alex in a couple of parsing projects, but I have failed when trying to combine a monadic Happy grammar (using the %monad and %lexer directives) together with an Alex generated okenizer, nor are there any such examples in the Happy and Alex distributions. Have anyone tried this combination and can give me some advice or a simple example? I've been doing some work on Alex recently, and getting it to work smoothly with Happy's monadic scheme is one of the goals. I'll post something when it's done, but if you want to have a look at the work-in-progress look in the CVS tree, under fptools/happy/alex on the branch simonm-hackery-branch. The other things I'm doing include making Alex's syntax more lex-like and Happy-like (mostly done), making the generated code more efficient in terms of both space and time (mostly done), and adding support for Unicode (not done, I'm still thinking about how best to do this - I have some ideas but suggestions are welcome). Cheers, Simon ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Anyone calculating Nash or Wardrop equilibria in Haskell?
Hello. Haskells declarativity is really useful to transform mathematical models into data types and algorithms. In the context of a seminary I have dealt with equilibria concepts (especially Nash and Wardrop equilibrium) in loss networks. (based on Non-cooperative routing in loss networks by Altman et al.) Thereby I have noticed that some algorithms are very easy to implement in Haskell, e.g. the state space or the blocking probability. Surely these algorithms are not efficient, they should just do their jobs. On the other hand there are algorithms, too, which appear to be really hard and long winded to implement, e.g. the equilibria by itself. My question: Is there an elegant way of programming a numerical solver of problems like given the conditions ... find a solution which minimizes/maximizes the following function Presumably there is no such way in general, but maybe someone can give a hint, how to tackle these kinds of problems. Or maybe there are some libraries doing this job. Thanks in advance and best greetings. Steffen Mazanek ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
RE: fundeps for extended Monad definition
The reason, which is thoroughly explained in Simon Peyton-Jones' message, is that the given type signature is wrong: it should read f1 :: (exists b. (C Int b) = Int - b) Right. Simon pointed out that this is a pretty useless function, but not entirely so, since the result of it is not of type 'forall b. b', but rather of 'forall b. C Int b = b'. Thus, if the C class has a function which takes a 'b' as an argument, then this value does have use. Hal Daume's original example works as well: newtype MM2 m a = MM2 (forall mb.(Monad2 m a mb) = mb) class Monad2 m a ma | m a - ma, ma - m a where return2 :: a - ma bind2 :: ma - (a - (MM2 m a)) - (MM2 m a) unused :: m a - () unused = \_ - () This wasn't quite my original example. The type of bind2 needs to be: bind2 :: ma - (a - (MM2 m b)) - (MM2 m b) Which does typecheck. However, you cannot seem to write instances of it: instance Monad2 [] a [a] where return2 x = [x] bind2 l f = MM2 (concatMap (unmm2 . f) l) where unmm2 (MM2 mb) = mb yields our friend cannot unify mb with [b], both in hugs and ghc. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
One-month alert to ICFP submission deadline
The submission deadline for ICFP -- the International Conference on Functional Programming -- is coming up soon: Saturday, March 29, which is four weeks away. The 2003 ICFP will be in Uppsala, Sweden on August 25-29, in conjunction with PPDP (Principles and Practice of Declarative Programming). Please take a moment to read the call for papers I've appended below, and see if you have a topic or result you would like to submit to the program committee. Please forward this notice to any relevant internal mailing lists, as well. See you in Sweden. -Olin Shivers program chairman === Eighth Annual ACM SIGPLAN International Conference on Functional Programming ICFP 2003 Call for Papers (Revised 2003/2/5) Affiliated with PLI 2003 August 25-29, 2003 Uppsala, Sweden http://www-users.cs.york.ac.uk/~colin/icfp2003.html http://www.cc.gatech.edu/icfp03/cfp.html --- * Important dates - Submission deadline 18:00 EST 29 March, 2003 (Saturday) Notification of acceptance rejection 19 May, 2003 Final paper due 16 June, 2003 Conference 25-29 August, 2003 * Scope --- ICFP 2003 seeks original papers on the full spectrum of the art, science, and practice of functional programming. The conference invites submissions on all topics ranging from principles to practice, from foundations to features, and from abstraction to application. The scope covers all languages that encourage programming with functions, including both purely applicative and imperative languages, as well as languages that support objects and concurrency. Topics of interest include, but are not limited to, the following: Foundations formal semantics, lambda calculus, type theory, monads, continuations, control, state, effects. Design Algorithms and data structures, modules and type systems, concurrency and distribution, components and composition, relations to object-oriented and logic programming, multiparadigm programming. Implementation abstract machines, compile-time and run-time optimization, just-in-time compilers, memory management. Interfaces to foreign functions, services, components and low-level machine resources. Transformation and analysis abstract interpretation, partial evaluation, program transformation, theorem proving, specification and verification. Software development techniques for functional programming design patterns, specification, verification and validation, debugging, test generation, tracing and profiling. Applications and domain-specific languages systems programming, scientific and numerical computing, symbolic computing and artificial intelligence, systems programming, databases, graphical user interfaces, multimedia programming, application scripting, system administration, distributed-systems construction, web programming. Practice and experience functional programming in education and industry, ramifications on other paradigms and computing disciplines. Functional pearls elegant, instructive examples of functional programming. Papers in the latter three categories need not necessarily report original research results; they may instead, for example, report practical experience that will be useful to others, re-usable programming idioms, or elegant new ways of approaching a problem. The key criterion for such a paper is that it makes a contribution from which other practitioners can benefit. It is not enough simply to describe a program! * Submission guidelines --- Due date time: Submissions must be filed at the web site by 18:00 EST on Saturday 29 March. Some convenient equivalents to 18:00 EST are New York: 6:00 PM = 18h00 San Francisco: 3:00 PM = 15h00 Chicago: 5:00 PM = 17h00 Paris: Midnight Hong Kong: 7:00 AM (30 March) UTC: 2300 For other time-zones/locations, see http://www.timeanddate.com/worldclock/fixedtime.html Submission URL: http://www.cc.gatech.edu/icfp03/submit Authors should submit a 100-200 word abstract and a full paper by 23:00 Universal Coordinated Time on Saturday, 29 March, 2003. Submissions should be no more than 12 pages (including bibliography and appendices) in standard ACM conference format: two columns, nine-point font on a ten-point baseline, with pages 20pc (3.33in) wide and 54pc (9in) tall, with a column gutter of 2pc (0.33in). Detailed formatting guidelines are available at http://www.acm.org/sigs/pubs/proceed/template.html, along with formatting templates or style files for LaTeX, Word Perfect, and Word. You don't need to include categories, keywords, etc., though you are welcome to do so. Also, note that the ACM copyright notice
RE: fundeps for extended Monad definition
Hello! It seems we can truly implement Monad2 without pushing the envelope too far. The solution and a few tests are given below. In contrast to the previous approach, here we lift the type variables rather than bury them. The principle is to bring the type logic programming at the level of classes and instances but avoid putting them at the level of their members. class TwoMonadific m a ma | m a - ma, ma - m a where unused :: m a - () unused = undefined instance TwoMonadific [] a [a] instance TwoMonadific Maybe a (Maybe a) class (TwoMonadific m a ma, TwoMonadific m b mb) = Monad2 m a b ma mb where return2 :: a - ma bind2 :: ma - (a - mb) - mb instance Monad2 [] a b [a] [b] where return2 x = [x] bind2 l f = concatMap f l instance Monad2 Maybe a b (Maybe a) (Maybe b) where return2 x = Just x bind2 Nothing f = Nothing bind2 (Just x) f = f x test1 = (return2 5) `bind2` (\n - [1..n]) `bind2` (\n - [1..n]) test2 = (return2 5) `bind2` Just `bind2` Just *Main test1 [1,1,2,1,2,3,1,2,3,4,1,2,3,4,5] *Main test2 Just 5 It all works in GHC. Hugs complaints about return2: ERROR /tmp/b.hs:11 - Ambiguous type signature in class declaration *** ambiguous type : Monad2 a b c d e = b - d *** assigned to: return2 My version of Hugs isn't up-to-date though. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re:
http://www.chinahtm.com 1, 2.CN 3ASP+ACCESS10 4 5 A B C D3721 0592-239101819 0592-2391098 [EMAIL PROTECTED] http://www.chinahtm.com [EMAIL PROTECTED] ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
