Re: [Haskell-cafe] ANNOUNCE: iteratee-compress 0.2.0.0
On 23 April 2011 19:29, Maciej Piechotka uzytkown...@gmail.com wrote: Iteratee-compress provides compressing and decompressing enumerators including flushing (using John Lato's implementation). Currently only gzip and bzip is provided but LZMA is planned. Changes from previous version: - Add BZip support Cool :) I notice the haddocks on hackage have not been generated; would this be due to libbz2-dev missing on the hackage server? Conrad. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] converting prefixes of CString - String
I have been reading Foreign.C.String but it does not seem to provide the functionality I was looking for. Let 'c2h' convert CStrings to Haskell Strings, and 'h2c' convert Haskell Strings to CStrings. (If I understand correctly, c2h . h2c === id, but h2c . c2h is not the identity on all inputs; or perhaps c2h is not defined for all CStrings. Probably this is all locale dependent.) I have an infinite Haskell String transferred byte-wise over a network; I would like to convert some prefix of the bytes received into a prefix of the String I started with. However, if I understand correctly, if s is a Haskell String it is not necessarily true that c2h (take n (h2c s)) is a prefix of s for all n. So I have two questions: Given a CString of the form cs = take n (h2c s), how do I know whether c2h cs is a prefix of s or not? Is there a way to recognize whether a CString is valid as opposed to truncated in the middle of a code point, or is this impossible? Better yet, given a CString cs = take n (h2c s), is there a way to find the maximal prefix cs' of cs such that c2h cs' is a prefix of s? If s == s1 ++ s2, is it necessarily true that s == (c2h (h2c s1)) ++ (c2h (h2c s2))? If so, then I can perform my conversion a bit at a time, otherwise I'd need to start from the beginning of the cstring each time I receive additional data. In practice, I think my solution will come down to restricting my program to only using the lower 128 characters, but I'd like to know how to handle this problem in full generality. Thanks, Eric ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] More ideas for controlled mutation
Edward Z. Yang wrote: Laziness can be viewed as a form of controlled mutation, where we overwrite a thunk with its actual value, thus only running the code once and reaping great time benefits. [..] Hash tables take advantage of this fact by simply chaining together values in a linked list if they land in the same bucket. Could we have similarly bucketized memoization? What we want here is for a *thunk to possibly evaluate to different values, but calls to the API be observationally equivalent.* That is, if the only way I can inspect a dictionary list is do a lookup, I don't care if my representation is [(1,4),(2,2)] or [(2,2),(1,4)]. An obvious way to do this is to use unsafePerformIO to read out an IORef stating the value currently being looked up, and have the thunk evaluate to the pair of that key and the result. There are some synchronization concerns, of course: ideally we would only take out a lock on the thunk once we realize that the value doesn't already exist in the memotable, but I don't think there's a way in GHC Haskell to observe if a value is a thunk or not (maybe such a mechanism would be useful?) The thing is that lazy evaluation is referentially transparent while I don't care about [(1,4),(2,2)] vs [(2,2),(1,4)] is not. In the latter case, you have a proof obligation to the compiler that your API does not expose the difference between these two values. But in Haskell, you have no way of convincing the compiler that you fulfilled that proof obligation! (At least, I don't see any obvious one. Maybe a clever abuse of parametricity helps.) It might be an option in Agda, though. In that light, it is entirely reasonable that you have to use unsafePerformIO . Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A small Darcs anomoly
On 24/04/2011 06:33 PM, Jason Dagit wrote: On Sun, Apr 24, 2011 at 2:05 AM, Andrew Coppin andrewcop...@btinternet.com mailto:andrewcop...@btinternet.com wrote: So I was a little surprised to discover that... Darcs doesn't actually support doing this. Darcs is only really interested in the result of applying *all* changes in a repo. It seems daft to me that you would design a sophisticated system for splitting history into independent chunks, and then not let me manipulate them independently. This is because of a deliberate choice that was made by David Roundy. In darcs, you never have multiple branches within a single darcs repository directory tree. Yes, this seems clear. I'm just wondering whether or not it's the best design choice. To get the effect you want, you simply create two repositories. One having only the patches for ghc 6.6 and one having the patches of ghc 7.0 and then you pull just the patches you want from 7.0 into 6.6. There are options to 'darcs get' that help you select the right set of patches to help you create the two repositories. It does mean that you duplicate information. You have [nearly] the same set of patches stored twice, and you're not really storing the history of the relationship between two branches, only the history of the branch itself. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to keep cabal and ghci package versions in sync?
Gracjan Polak schrieb: Hi all, I have a project with a .cabal file listing package dependencies using the usual version constraints ==X.Y.* Z.W or =K.J syntax. Standard route cabal configure; cabal build works correctly as it is able to select working set of package versions. You can manually select packages for GHCi with '-package' option. However I do not know a way to automatically syncronise this with the dependencies from the Cabal file. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Trouble with currying and uncurrying...
Hi, I'm reading The Craft of Functional Programming and I found something I don't understand in page 185. It says: Suppose first that we want to write a curried version of a function g, which is itself uncurried and of type (a,b) - c. curry g This funtion expects its arguments as a pair, but its curried version, curry g, will take them separately - we therefore have to form them into a pair before applying g to them: curry :: ((a,b) - c) - (a - b - c) curry g x y = g (x,y) curry multiplyUC will be exactly the same function as multiply. OK, I have tried it and it works, but I don't understand the syntax for curry. Until now I have encountered only functions that take the same number of arguments as the function definition or less (partial application), but this syntax looks a bit new to me. curry is supposed to have as its argument one function of type (a,b) - c and produce another function, but then the second line gives three arguments to curry, the function itself and the variables x and y. What I'm missing here? Thanks a lot, Ángel de Vicente -- http://www.iac.es/galeria/angelv/ High Performance Computing Support PostDoc Instituto de Astrofísica de Canarias - ADVERTENCIA: Sobre la privacidad y cumplimiento de la Ley de Protección de Datos, acceda a http://www.iac.es/disclaimer.php WARNING: For more information on privacy and fulfilment of the Law concerning the Protection of Data, consult http://www.iac.es/disclaimer.php?lang=en ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble with currying and uncurrying...
On 25 April 2011 14:11, Angel de Vicente ang...@iac.es wrote: curry :: ((a,b) - c) - (a - b - c) is the same as: curry :: ((a,b) - c) - a - b - c HTH, Ozgur ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble with currying and uncurrying...
On 25 April 2011 14:11, Angel de Vicente ang...@iac.es wrote: curry :: ((a,b) - c) - (a - b - c) curry g x y = g (x,y) Is expressing curry this way more illuminating? curry :: ((a,b) - c) - (a - b - c) curry g = \x y - g (x,y) That is, curry is a function taking one argument that produces a result function taking two arguments. In Haskell - the type signature: curry :: ((a,b) - c) - (a - b - c) ... can mean either form. Though this is a quirk of Haskell, in the language Clean, for example, the parens in the type signature mean what they say so only only my second definition is allowed, the first version won't compile. Best wishes Stephen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble with currying and uncurrying...
On 25 April 2011 14:11, Angel de Vicente ang...@iac.es wrote: OK, I have tried it and it works, but I don't understand the syntax for curry. Until now I have encountered only functions that take the same number of arguments as the function definition or less (partial application), but this syntax looks a bit new to me. curry is supposed to have as its argument one function of type (a,b) - c and produce another function, but then the second line gives three arguments to curry, the function itself and the variables x and y. What I'm missing here? You can think of all functions in Haskell as taking only one argument. So curry has one argument, which is a function that takes a pair (in this case g). The value of curry g is another function (the curried version of g) which takes two arguments. This is clearer when written out like so: g :: (a, b) - c h :: a - b - c h = curry g h x y = g (x, y) So by simple substitution we can see that curry g x y = g (x, y) It might be even clearer if we add parentheses, since function application associates to the left: (curry g) x y = g (x, y) Hope this clears things up. For more information you could have a look at the Gentle Introduction's section on functions: http://www.haskell.org/tutorial/functions.html Benedict. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble with currying and uncurrying...
Hi, On 25/04/11 14:20, Ozgur Akgun wrote: On 25 April 2011 14:11, Angel de Vicente ang...@iac.es mailto:ang...@iac.es wrote: curry :: ((a,b) - c) - (a - b - c) is the same as: curry :: ((a,b) - c) - a - b - c thanks, it makes sense now. Somehow I thought that adding the parenthesis in ...- (a - b - c) was something special and that I couldn't get rid of them (in the same sense as I cannot get rid of the parenthesis in the first part and write: curry :: (a,b) - c - a - b - c Thanks, Ángel -- http://www.iac.es/galeria/angelv/ High Performance Computing Support PostDoc Instituto de Astrofísica de Canarias - ADVERTENCIA: Sobre la privacidad y cumplimiento de la Ley de Protecci�n de Datos, acceda a http://www.iac.es/disclaimer.php WARNING: For more information on privacy and fulfilment of the Law concerning the Protection of Data, consult http://www.iac.es/disclaimer.php?lang=en ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble with currying and uncurrying...
Hi, On 25/04/11 14:21, Stephen Tetley wrote: On 25 April 2011 14:11, Angel de Vicenteang...@iac.es wrote: curry :: ((a,b) - c) - (a - b - c) curry g x y = g (x,y) Is expressing curry this way more illuminating? curry :: ((a,b) - c) - (a - b - c) curry g = \x y - g (x,y) That is, curry is a function taking one argument that produces a result function taking two arguments. In Haskell - the type signature: curry :: ((a,b) - c) - (a - b - c) ... can mean either form. Though this is a quirk of Haskell, in the language Clean, for example, the parens in the type signature mean what they say so only only my second definition is allowed, the first version won't compile. This was my first encounter with this syntax, but it was a bit confusing. curry :: ((a,b) - c) - a - b - c is much clearer to me, and once partial application is understood it is no problem to see what curry f or curry f x y mean. But to me (at this point in my Haskell trip) it would make more sense that once you put the parentheses as in the original definition, no partial application is allowed and so the lambda notation is required. Thanks a lot, Ángel de Vicente -- http://www.iac.es/galeria/angelv/ High Performance Computing Support PostDoc Instituto de Astrofísica de Canarias - ADVERTENCIA: Sobre la privacidad y cumplimiento de la Ley de Protección de Datos, acceda a http://www.iac.es/disclaimer.php WARNING: For more information on privacy and fulfilment of the Law concerning the Protection of Data, consult http://www.iac.es/disclaimer.php?lang=en ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Storing failing testcases for QuickCheck
Roel van Dijk wrote: On 24 April 2011 01:49, wren ng thornton w...@freegeek.org wrote: I would *love* there to be a tool which (a) automatically saves failing QuickCheck values to disk, and (b) automates using HUnit to load those in and test them. I'm not so sure that QuickCheck should be doing the second step of that since that'd really mess with the QuickCheck infrastructure; once you have the code for reading from disk, it'd be trivial to just use HUnit. Maybe this is a job for test-framework? I think the API's of QuickCheck and HUnit expose enough information for this to be possible. I've hacked something together: [1]. It doesn't use neither HUnit nor test- framework, but I can see, why that would probably be better. It seems to do the job for me at the moment. [1] https://patch-tag.com/r/shahn/QuickCheckStore/home ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
So it appears this is a bug with JSONb-1.0.2. There's a new version out. IS the answer to use that, or to patch this version? On Mon, Apr 25, 2011 at 1:48 PM, Michael Litchard mich...@schmong.org wrote: Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
On Mon, Apr 25, 2011 at 2:44 PM, Michael Litchard mich...@schmong.org wrote: So it appears this is a bug with JSONb-1.0.2. There's a new version out. IS the answer to use that, or to patch this version? If there is a new version, and you indeed need JSONb for something, then you should use the newer version (yesod doesn't depend on it, so I'm a bit unsure why it came up...). --Rogan On Mon, Apr 25, 2011 at 1:48 PM, Michael Litchard mich...@schmong.org wrote: Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ 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] errors while installing yesod 0.8
I think something that yesod uses, uses JSONb. Also, I think I have borked my haskell environment to the point where it may be best to zap it and start over. On Mon, Apr 25, 2011 at 3:05 PM, Rogan Creswick cresw...@gmail.com wrote: On Mon, Apr 25, 2011 at 2:44 PM, Michael Litchard mich...@schmong.org wrote: So it appears this is a bug with JSONb-1.0.2. There's a new version out. IS the answer to use that, or to patch this version? If there is a new version, and you indeed need JSONb for something, then you should use the newer version (yesod doesn't depend on it, so I'm a bit unsure why it came up...). --Rogan On Mon, Apr 25, 2011 at 1:48 PM, Michael Litchard mich...@schmong.org wrote: Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ 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] Data.Enumerator.Text.utf8 not constant memory?
Hi, I am learning iteratees, and as a starter project I wanted to use expat- enumerator to parse a 2 gigabyte XML file. I expected to be able to do what SAX does in Java, i.e. to avoid loading the whole 2 gigabytes into memory. For warm-up, I wrote an iteratee to count lines in the file, and it does load the whole file into memory! After profiling, I see that the problem was Data.Enumerator.Text.utf8, it allocates up to 60 megabytes when run on a 40 megabyte test file. Any suggestions how to fix Text.utf8, or what people do for parsing UTF-8 encoded text files with iteratees? Thanks! Here is my code and profiling results: http://i.imgur.com/XEI1v.png http://hpaste.org/46037/counting_lines_with_iteratees http://hpaste.org/46038/counting_lines_with_iteratees ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
Oh yeah, this began while trying to install by hand authenticate-0.8.2.2 On Mon, Apr 25, 2011 at 3:10 PM, Michael Litchard mich...@schmong.org wrote: I think something that yesod uses, uses JSONb. Also, I think I have borked my haskell environment to the point where it may be best to zap it and start over. On Mon, Apr 25, 2011 at 3:05 PM, Rogan Creswick cresw...@gmail.com wrote: On Mon, Apr 25, 2011 at 2:44 PM, Michael Litchard mich...@schmong.org wrote: So it appears this is a bug with JSONb-1.0.2. There's a new version out. IS the answer to use that, or to patch this version? If there is a new version, and you indeed need JSONb for something, then you should use the newer version (yesod doesn't depend on it, so I'm a bit unsure why it came up...). --Rogan On Mon, Apr 25, 2011 at 1:48 PM, Michael Litchard mich...@schmong.org wrote: Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ 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] errors while installing yesod 0.8
On Mon, Apr 25, 2011 at 3:10 PM, Michael Litchard mich...@schmong.org wrote: I think something that yesod uses, uses JSONb. Odd. I just checked the transitive dependencies of yesod-0.8.0 (with cab) and it doesn't seem to have that dependency. It could be system-specific, though. It would be nice to figure out what is depending on that version of JSONb so we could better determine if upgrading will break anything. --Rogan Also, I think I have borked my haskell environment to the point where it may be best to zap it and start over. On Mon, Apr 25, 2011 at 3:05 PM, Rogan Creswick cresw...@gmail.com wrote: On Mon, Apr 25, 2011 at 2:44 PM, Michael Litchard mich...@schmong.org wrote: So it appears this is a bug with JSONb-1.0.2. There's a new version out. IS the answer to use that, or to patch this version? If there is a new version, and you indeed need JSONb for something, then you should use the newer version (yesod doesn't depend on it, so I'm a bit unsure why it came up...). --Rogan On Mon, Apr 25, 2011 at 1:48 PM, Michael Litchard mich...@schmong.org wrote: Following the install trail I run into this problem mlitchard@apotheosis:~$ cab install JSONb-1.0.2 Resolving dependencies... Configuring JSONb-1.0.2... Preprocessing library JSONb-1.0.2... Preprocessing executables for JSONb-1.0.2... Building JSONb-1.0.2... [1 of 7] Compiling Text.JSON.Escape ( Text/JSON/Escape.hs, dist/build/Text/JSON/Escape.o ) [2 of 7] Compiling Text.JSONb.Simple ( Text/JSONb/Simple.hs, dist/build/Text/JSONb/Simple.o ) [3 of 7] Compiling Text.JSONb.Decode ( Text/JSONb/Decode.hs, dist/build/Text/JSONb/Decode.o ) Text/JSONb/Decode.hs:56:33: Ambiguous occurrence `number' It could refer to either `Text.JSONb.Decode.number', defined at Text/JSONb/Decode.hs:118:0 or `Attoparsec.number', imported from Data.Attoparsec.Char8 at Text/JSONb/Decode.hs:25:0-52 cabal: Error: some packages failed to install: JSONb-1.0.2 failed during the building phase. The exception was: ExitFailure 1 How do I clear up this ambiguity? On Mon, Apr 25, 2011 at 1:24 PM, Michael Litchard mich...@schmong.org wrote: I started mindlessly pasting in the output, and the following lept out at me: , package authenticate-0.8.2.2-cc3ed2c523ecbf1ad123c3468785149e is unusable due to missing or recursive dependencies: http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 package http-enumerator-0.3.1-719bcd77e1dcb62efc9cf9b4f0b72271 is unusable due to missing or recursive dependencies: attoparsec-enumerator-0.2.0.3-4978ab2dc4d87b7b724534bbfdcb07f1 package json-enumerator-0.0.1-7d4b724ae8c9b5ffa92da26856c4e1f1 is unusable due to missing or recursive dependencies: blaze-builder-enumerator-0.2.0.1-23e6e1f270358d3329f627e3a5ce8838 package wai-extra-0.3.2-f8378ad4a5cc6f375d96b718876384fa is unusable due to missing or recursive dependencies: There's more of the same I'm leaving out. I'm going to see if I can go somewhere with these error messages. If I totally hose things, I'll let you guys know. On Tue, Apr 19, 2011 at 4:45 PM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 20 April 2011 01:22:20, Michael Litchard wrote: So what else can I try? $ cabal install -v3 monad-control That should give some hints at which point exactly things fail. ___ 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] errors while installing yesod 0.8
On 26 April 2011 00:20, Rogan Creswick cresw...@gmail.com wrote: It would be nice to figure out what is depending on that version of JSONb so we could better determine if upgrading will break anything. Maybe the following helps: http://bifunctor.homelinux.net/~roel/cgi-bin/hackage-scripts/revdeps/JSONb Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.10.0
On Friday 22 April 2011 12:40:17, Hamish Mackenzie wrote: Yesterday we uploaded our official 0.10.0 release (0.10.0.4) to Hackage I'm trying to try it, but I run into a couple of problems. Most are probably me looking in the wrong places, so let's begin with those. By default, the editor pane is on the left hand side and the module browser or whatnot on the right. Very irritating. How do I switch the positions? I tried swapping LeftP and RightP in Edit Prefs - Initial Pane positions, but to no avail. Autocomplete starts at the first letter of any new word, so writing a function definition bar j | j == 0 = whatever | otherwise = somethingElse requires paying attention and taking some action to not end up with bar join| j == whatever ... How do I configure autocompletion to only begin after three or four letters have been typed? Decreasing indentation via backspace goes one column per backspace, how can I configure it to go to the next (previous) tab position on backspace in the leading whitespace of a line? Now, those configuration questions out of the way: On first startup, I pointed leksah to ~/.cabal/packages/hackage.haskell.org for sources (hoping it would know to unpack them and copy them to ~/.leksah-0.10/packageSources, run haddock on them and what else it needs). It did indeed copy a bunch of sources there and invoked cabal and ghc a number of times, but it left out about half of the installed packages. It used an awful lot of memory to do that, peak about 1300MB virtual, 800MB resident, which means swapping and thrashing (unless I shut down practically everything else - I have only 1G of RAM). Okay, for collecting metadata on the first startup, I could live with that (though, if it handled packages sequentially, it should use less memory). But on the second startup and the third, although it didn't invoke cabal or ghc anymore, the memory usage was about the same, effectively knocking out my system for more than ten minutes. On the third, I had not enough patience and killed it, leksah-server showed no signs of stopping within two minutes after kill -TERM, so I had to kill -KILL it. What can I do to make leksah a good memory-citizen? With the current behaviour, it is unusable for me, unfortunately. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell from SML - referrential Transparency?!
I've been working on Haskell for quite a while and it's not too often that a beginner shows me a new trick--this trick with trace seems really cool and I hadn't seen it before. f x | trace (f ++ show x) False = undefined f ... -- rest of regular definition Makes it really easy to add the trace and then later comment it out. One problem I always have with traces the usual way is that adding/removing them is kind of annoying--it can change the indentation of your code, etc. So this trick is really useful! Thanks Gregory! -- ryan On Tue, Apr 19, 2011 at 12:38 PM, Gregory Guthrie guth...@mum.edu wrote: Oops; No - my (further) mistake. It is not IO() - f1 returns a data structure which implements Show, and the test is really: Test1 = do print Test1: print f1 (etc..) Thanks for the alert on trace. I used it like this: allocate :: Store - (Store, Location) allocate ( Store(bot,top,sto) ) | trace(allocate ++ show bot ++ show top) False = undefined allocate ( Store(bot,top,sto) ) = let newtop = top+1 and it does seem to show every allocation on the first run of f1, but then nothing on the second. SO it is not just a first call to allocate, but all calls under an invocation of f1 that don't show. Makes me wonder if f1 is even being re-evaluated. I did post the code - but don't expect anyone to really wade through and debug for me! :-) (The issues that I am asking about are a9b, a9bb at line 435, 438) http://hpaste.org/45851/haskell_from_sml_question thanks for the help. --- -Original Message- From: Daniel Fischer [mailto:daniel.is.fisc...@googlemail.com] Sent: Tuesday, April 19, 2011 2:16 PM To: haskell-cafe@haskell.org Cc: Gregory Guthrie Subject: Re: [Haskell-cafe] Haskell from SML - referrential Transparency?! On Tuesday 19 April 2011 21:10:09, Gregory Guthrie wrote: I am pretty new to Haskell, so need some clarification. I am porting some code from SML, and getting a result that surprises me. I basically have some functions which work like this: f1 = fa fb fc test1 = do print test1: f1 So f1 :: IO something Being an IO-action, f1 can return different things in different invocations since the world in which it runs has changed (it might read a file which was modified between the first and the second invocation, for example). But I ran a few tests, and got odd results - so I ran the same test function twice, and got different results - that was my surprise. I did this: f1 = fa fb fc f2 = fa fb fc test2 = do print test1: f1 f2 and I get different results from the two executions (f1,f2), even though they have exactly the same definition. Reversing their order, gives the exact same results (i.e. the results are still different, and in the same original order as f2;f1). Even doing (f1;f1) gives two different results. Depending on what f1 does, that may be perfectly normal or a serious bug. We'd need to see more of the code to determine which. Seems to me that by referential transparency, I should always get the same result from the function(s). So, I added some Debug.trace to the argument functions which are used, and I get a trace from the first call(s), but none from the second one(s), although I do get the result from each. Did you do it in the form fa = trace (fa) realFa ? Then the trace is only evaluated the first time fa is evaluated, even if fa is called later again. It is as if because of the laziness, it someone cached some of the intermediate results, so did not re-invoke the functions. Anyway, totally confused. I must be missing something significant here. Thanks for any clarification! (The original code is a bit long, so I did not include here...) http://hpaste.org/ perhaps? ___ 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] ANN: Leksah 0.10.0
Daniel Fischer wrote: On Friday 22 April 2011 12:40:17, Hamish Mackenzie wrote: Yesterday we uploaded our official 0.10.0 release (0.10.0.4) to Hackage I'm trying to try it, but I run into a couple of problems. Most are probably me looking in the wrong places, so let's begin with those. By default, the editor pane is on the left hand side and the module browser or whatnot on the right. Very irritating. How do I switch the positions? I tried swapping LeftP and RightP in Edit Prefs - Initial Pane positions, but to no avail. Well, it is a bit more intricate to invert the sides. After * swapping LeftP and RightP in Edit Prefs - Initial Pane positions * Close all panes and pane groups. (You may leave an editor window open, so that you better see what happens in the next steps). * Collapse all (Hit Ctrl-1 - 2 times) * Split vertical (Hit Ctrl-2), put the focus to the left, split horizontal (Hit Ctrl-3) * Go to Panes Menu and reopen the Log and the Browser and an editor Window * Configure tabs as you like * Save the session or restart Leksah Daniel Fischer wrote: Autocomplete starts at the first letter of any new word, so writing a function definition bar j | j == 0 = whatever | otherwise = somethingElse requires paying attention and taking some action to not end up with bar join| j == whatever ... How do I configure autocompletion to only begin after three or four letters have been typed? Go to Edit Prefs - GUI Options, and select Complete only on Hotkey, then hit Ctrl-Space if you want completion. Daniel Fischer wrote: Decreasing indentation via backspace goes one column per backspace, how can I configure it to go to the next (previous) tab position on backspace in the leading whitespace of a line? You can't do this currently, but you can post a wish for enhancement to our issue tracker. Daniel Fischer wrote: Now, those configuration questions out of the way: On first startup, I pointed leksah to ~/.cabal/packages/hackage.haskell.org for sources (hoping it would know to unpack them and copy them to ~/.leksah-0.10/packageSources, run haddock on them and what else it needs). Please try to run Leksah with the default config (~/.leksah-0.10/packageSources) Daniel Fischer wrote: It did indeed copy a bunch of sources there and invoked cabal and ghc a number of times, but it left out about half of the installed packages. It used an awful lot of memory to do that, peak about 1300MB virtual, 800MB resident, which means swapping and thrashing (unless I shut down practically everything else - I have only 1G of RAM). Okay, for collecting metadata on the first startup, I could live with that (though, if it handled packages sequentially, it should use less memory). But on the second startup and the third, although it didn't invoke cabal or ghc anymore, the memory usage was about the same, effectively knocking out my system for more than ten minutes. On the third, I had not enough patience and killed it, leksah-server showed no signs of stopping within two minutes after kill -TERM, so I had to kill -KILL it. What can I do to make leksah a good memory-citizen? With the current behaviour, it is unusable for me, unfortunately. Indeed leksah may use more memory on the first run (actually it is ghc, which uses it). But on consecutive starts it may use about/up to 150MB, but not the numbers you give. So please try to run Leksah with the default config, and see if the problem remains. Jürgen -- View this message in context: http://haskell.1045720.n5.nabble.com/ANN-Leksah-0-10-0-tp4332741p4339787.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] errors while installing yesod 0.8
In case this ever gets googled ... I'm pretty sure this problem had to do with my environment. I removed $HOME/.cabal and $HOME/.ghc, and upgraded to the latest stable haskell platform. yesod 0.8 has installed fine. I'm not sure what the exact problem was however. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.10.0
On 26 April 2011 11:03, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: Decreasing indentation via backspace goes one column per backspace, how can I configure it to go to the next (previous) tab position on backspace in the leading whitespace of a line? shifttab works, but it is a bit dumb. Changing backspace is on my wish list too. I think we should make it look at the text above to find the correct indentation points. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Inputs to classic FRP: unsafeInterleaveIO/unsafePerformIO
As far as I can tell, with classic FRP implementations (those which use behaviors as a first-class abstraction), the only way to create a behavior or event based on some external input (for instance keypresses or microphone input) is to do something with unsafePerformIO or unsafeInterleaveIO. A behavior is a value, which when evaluated at a specific time would have to either block its evaluation until input could be read, or check the input at that particular time. Is there any other way of implementing external behaviors besides that? -- Edward Amsden Student Computer Science Rochester Institute of Technology www.edwardamsden.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Enumerator.Text.utf8 not constant memory?
[CC'ing John Millikin, enumerator's maintainer] On Mon, Apr 25, 2011 at 7:10 PM, Skirmantas Kligys skirmantas.kli...@gmail.com wrote: I expected to be able to do what SAX does in Java, i.e. to avoid loading the whole 2 gigabytes into memory. For warm-up, I wrote an iteratee to count lines in the file, and it does load the whole file into memory! After profiling, I see that the problem was Data.Enumerator.Text.utf8, it allocates up to 60 megabytes when run on a 40 megabyte test file. It seems to me that this is a bug in enumerator's strict fold not being strict at all =). The current version 0.4.9.1 of Data.Enumerator.List.fold is -- | Consume the entire input stream with a strict left fold, one element -- at a time. -- -- Since: 0.4.8 fold :: Monad m = (b - a - b) - b - Iteratee a m b fold step = continue . loop where f = L.foldl' step loop acc stream = case stream of Chunks [] - continue (loop acc) Chunks xs - continue (loop (f acc xs)) EOF - yield acc EOF Note that the list fold is strict (f = Data.List.foldl' step), *however* the acc parameter of loop isn't strict at all! It just creates a big, fat thunk with references to all of you input =(. But the fix is extremely easy, just change the 'Chunks xs' line to Chunks xs - continue (loop $! f acc xs) Using only your iterLinesWc test with a 105 MiB file (a movie I had lying around), with enumerator's definition it takes 220 MiB of memory and 1.3~1.5 seconds according to +RTS -s. By doing only this very change above, it takes 2 MiB of memory (100x improvement :P) and 0.8~0.9 seconds. John Millikin, could you please apply the attached patch? =) Cheers, -- Felipe. # Bazaar merge directive format 2 (Bazaar 0.90) # revision_id: felipe.le...@gmail.com-20110426020019-mad7rofbt62zwt49 # target_branch: http://john-millikin.com/branches/enumerator/0.4/ # testament_sha1: ff7491ebbe8698c6cad156203566aabd5aed # timestamp: 2011-04-25 23:01:15 -0300 # base_revision_id: jmilli...@gmail.com-20110329181202-\ # pzq011f39m787xld # # Begin patch === modified file 'enumerator/src/list-analogues.anansi' --- enumerator/src/list-analogues.anansi 2011-03-29 05:24:03 + +++ enumerator/src/list-analogues.anansi 2011-04-26 02:00:19 + @@ -19,7 +19,7 @@ f = L.foldl' step loop acc stream = case stream of Chunks [] - continue (loop acc) - Chunks xs - continue (loop (f acc xs)) + Chunks xs - continue (loop $! f acc xs) EOF - yield acc EOF : @@ -29,7 +29,7 @@ - Iteratee a m b foldM step = continue . loop where f = CM.foldM step - + loop acc stream = acc `seq` case stream of Chunks [] - continue (loop acc) Chunks xs - lift (f acc xs) = continue . loop @@ -134,7 +134,7 @@ concatMapM f = checkDone (continue . step) where step k EOF = yield (Continue k) EOF step k (Chunks xs) = loop k xs - + loop k [] = continue (step k) loop k (x:xs) = do fx - lift (f x) @@ -180,7 +180,7 @@ concatMapM f = checkDone (continue . step) where step k EOF = yield (Continue k) EOF step k (Chunks xs) = loop k (BL.unpack (BL.fromChunks xs)) - + loop k [] = continue (step k) loop k (x:xs) = do fx - lift (f x) @@ -206,7 +206,7 @@ concatMapM f = checkDone (continue . step) where step k EOF = yield (Continue k) EOF step k (Chunks xs) = loop k (TL.unpack (TL.fromChunks xs)) - + loop k [] = continue (step k) loop k (x:xs) = do fx - lift (f x) @@ -222,7 +222,7 @@ mapAccum f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = case f s x of (s', ai) - k (Chunks [ai]) == @@ -233,7 +233,7 @@ mapAccumM f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = do (s', ai) - lift (f s x) @@ -247,7 +247,7 @@ mapAccum f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = case B.uncons x of Nothing - loop s k xs @@ -260,7 +260,7 @@ mapAccumM f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = case B.uncons x of Nothing - loop s k xs @@ -276,7 +276,7 @@ mapAccum f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = case T.uncons x of Nothing - loop s k xs @@ -289,7 +289,7 @@ mapAccumM f s0 = checkDone (continue . step s0) where step _ k EOF = yield (Continue k) EOF step s k (Chunks xs) = loop s k xs - + loop s k [] = continue (step s k) loop s k (x:xs) = case T.uncons x of Nothing -
Re: [Haskell-cafe] Inputs to classic FRP: unsafeInterleaveIO/unsafePerformIO
Of course, you could have the 'interpretation' function be non-pure. For example: -- Library functions for a hypothetical FRP system pollEvent :: IO [a] - Event a behavior :: a - Event a - Behavior a accumB :: b - (b - a - b) - Event a - Behavior b accumE :: b - (b - a - b) - Event a - Event b union :: Event a - Event a - Event a runFRP :: (a - IO Bool) - Behavior a - IO () -- Event Behavior become instances of Functor Applicative -- and now a hypothetical implementation data Event a where Event :: s -- initial state - (s - IO ([a], s)) -- tick - Event a data Behavior a = Behavior a (Event a) pollEvent act = Event () $ \() - do xs - act return (xs, ()) behavior = Behavior union (Event sL0 tickL) (Event sR0 tickR) = Event (sL0,sR0) tick where tick (sL, sR) = do (ls, sL') - tickL sL (rs, sR') - tickR sR return (ls ++ rs, (sL', sR')) accumB b0 f e = Behavior b0 $ accumE b f e accumE b0 f (Event s0 tickE) = Event (b0, s0) tick where tick (b, s) = do (as, s') - tickE s let bs = scanl f b as return (bs, (last bs, s')) -- Functor, Applicative instances are pretty easy and left as an exercise runFRP tick (Behavior b0 (Event s0 e)) = runFRP' b0 s0 where runFRP' b s = do (bs, s') - e s0 let val = last (b:bs) k - tick b when k $ runFRP tick (Behavior k - tick b -- sample application keypress :: Event Char keypress = pollEvent getCurrentPressedKeys where getCurrentPressedKeys = undefined -- exercise for the reader On Mon, Apr 25, 2011 at 5:28 PM, Edward Amsden eca7...@cs.rit.edu wrote: As far as I can tell, with classic FRP implementations (those which use behaviors as a first-class abstraction), the only way to create a behavior or event based on some external input (for instance keypresses or microphone input) is to do something with unsafePerformIO or unsafeInterleaveIO. A behavior is a value, which when evaluated at a specific time would have to either block its evaluation until input could be read, or check the input at that particular time. Is there any other way of implementing external behaviors besides that? -- Edward Amsden Student Computer Science Rochester Institute of Technology www.edwardamsden.com ___ 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] Inputs to classic FRP: unsafeInterleaveIO/unsafePerformIO
Mail fail, haha. Code fixed. For example: -- Library functions for a hypothetical FRP system pollEvent :: IO [a] - Event a behavior :: a - Event a - Behavior a accumB :: b - (b - a - b) - Event a - Behavior b accumE :: b - (b - a - b) - Event a - Event b union :: Event a - Event a - Event a runFRP :: (a - IO Bool) - Behavior a - IO () -- Event Behavior become instances of Functor Applicative -- and now a hypothetical implementation data Event a where Event :: s -- initial state - (s - IO ([a], s)) -- tick - Event a data Behavior a = Behavior a (Event a) pollEvent act = Event () $ \() - do xs - act return (xs, ()) behavior = Behavior union (Event sL0 tickL) (Event sR0 tickR) = Event (sL0,sR0) tick where tick (sL, sR) = do (ls, sL') - tickL sL (rs, sR') - tickR sR return (ls ++ rs, (sL', sR')) accumB b0 f e = Behavior b0 $ accumE b f e accumE b0 f (Event s0 tickE) = Event (b0, s0) tick where tick (b, s) = do (as, s') - tickE s let bs = scanl f b as return (bs, (last bs, s')) -- Functor, Applicative instances are pretty easy and left as an exercise runFRP tick (Behavior b0 (Event s0 e)) = runFRP' b0 s0 where runFRP' b s = do (bs, s') - e s0 let b' = last (b:bs) k - tick b' when k $ runFRP' b' s' -- sample application keypress :: Event Char keypress = pollEvent getCurrentPressedKeys where getCurrentPressedKeys = undefined -- exercise for the reader -- application prints the last key you pressed until you press 'q' main = runFRP tick keypress where tick k = print k return (k /= 'q') ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Enumerator.Text.utf8 not constant memory?
Yay, much better! Now iterLinesWc works within 4 kilobytes, and iterLinesMine within 22 kilobytes, both nicely bounded. Thanks a lot for your help, Felipe! On Mon, Apr 25, 2011 at 7:03 PM, Felipe Almeida Lessa felipe.le...@gmail.com wrote: [CC'ing John Millikin, enumerator's maintainer] On Mon, Apr 25, 2011 at 7:10 PM, Skirmantas Kligys skirmantas.kli...@gmail.com wrote: I expected to be able to do what SAX does in Java, i.e. to avoid loading the whole 2 gigabytes into memory. For warm-up, I wrote an iteratee to count lines in the file, and it does load the whole file into memory! After profiling, I see that the problem was Data.Enumerator.Text.utf8, it allocates up to 60 megabytes when run on a 40 megabyte test file. It seems to me that this is a bug in enumerator's strict fold not being strict at all =). The current version 0.4.9.1 of Data.Enumerator.List.fold is -- | Consume the entire input stream with a strict left fold, one element -- at a time. -- -- Since: 0.4.8 fold :: Monad m = (b - a - b) - b - Iteratee a m b fold step = continue . loop where f = L.foldl' step loop acc stream = case stream of Chunks [] - continue (loop acc) Chunks xs - continue (loop (f acc xs)) EOF - yield acc EOF Note that the list fold is strict (f = Data.List.foldl' step), *however* the acc parameter of loop isn't strict at all! It just creates a big, fat thunk with references to all of you input =(. But the fix is extremely easy, just change the 'Chunks xs' line to Chunks xs - continue (loop $! f acc xs) Using only your iterLinesWc test with a 105 MiB file (a movie I had lying around), with enumerator's definition it takes 220 MiB of memory and 1.3~1.5 seconds according to +RTS -s. By doing only this very change above, it takes 2 MiB of memory (100x improvement :P) and 0.8~0.9 seconds. John Millikin, could you please apply the attached patch? =) Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Enumerator.Text.utf8 not constant memory?
*sigh* Another fine entry for john-millikin-is-an-idiot.txt Thank you for the patch Felipe, and for the bug report Skirmantas. I have uploaded 0.4.10 to Hackage. My sincere apologies for the inconvenience. On Mon, Apr 25, 2011 at 19:03, Felipe Almeida Lessa felipe.le...@gmail.com wrote: [CC'ing John Millikin, enumerator's maintainer] On Mon, Apr 25, 2011 at 7:10 PM, Skirmantas Kligys skirmantas.kli...@gmail.com wrote: I expected to be able to do what SAX does in Java, i.e. to avoid loading the whole 2 gigabytes into memory. For warm-up, I wrote an iteratee to count lines in the file, and it does load the whole file into memory! After profiling, I see that the problem was Data.Enumerator.Text.utf8, it allocates up to 60 megabytes when run on a 40 megabyte test file. It seems to me that this is a bug in enumerator's strict fold not being strict at all =). The current version 0.4.9.1 of Data.Enumerator.List.fold is -- | Consume the entire input stream with a strict left fold, one element -- at a time. -- -- Since: 0.4.8 fold :: Monad m = (b - a - b) - b - Iteratee a m b fold step = continue . loop where f = L.foldl' step loop acc stream = case stream of Chunks [] - continue (loop acc) Chunks xs - continue (loop (f acc xs)) EOF - yield acc EOF Note that the list fold is strict (f = Data.List.foldl' step), *however* the acc parameter of loop isn't strict at all! It just creates a big, fat thunk with references to all of you input =(. But the fix is extremely easy, just change the 'Chunks xs' line to Chunks xs - continue (loop $! f acc xs) Using only your iterLinesWc test with a 105 MiB file (a movie I had lying around), with enumerator's definition it takes 220 MiB of memory and 1.3~1.5 seconds according to +RTS -s. By doing only this very change above, it takes 2 MiB of memory (100x improvement :P) and 0.8~0.9 seconds. John Millikin, could you please apply the attached patch? =) Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Enumerator.Text.utf8 not constant memory?
On Tue, Apr 26, 2011 at 12:06 AM, John Millikin jmilli...@gmail.com wrote: *sigh* Another fine entry for john-millikin-is-an-idiot.txt Thank you for the patch Felipe, and for the bug report Skirmantas. I have uploaded 0.4.10 to Hackage. My sincere apologies for the inconvenience. But I am sure that john-millikin-is-great.txt must be increasing like a memory leak ;). Thanks for the quick upload, and there's no need for apologies. Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Enumerator.Text.utf8 not constant memory?
John, Thanks for a very quick fix, and thanks for making the enumerator library. I tried to learn iteratees first from iteratee library but got hopelessly confused within minutes. Now with your library and Snoyman's 3 part tutorial (http://www.yesodweb.com/blog/enumerators-tutorial-part-1) I at least have some basic understanding I can build on. On Mon, Apr 25, 2011 at 8:06 PM, John Millikin jmilli...@gmail.com wrote: *sigh* Another fine entry for john-millikin-is-an-idiot.txt Thank you for the patch Felipe, and for the bug report Skirmantas. I have uploaded 0.4.10 to Hackage. My sincere apologies for the inconvenience. On Mon, Apr 25, 2011 at 19:03, Felipe Almeida Lessa felipe.le...@gmail.com wrote: [CC'ing John Millikin, enumerator's maintainer] On Mon, Apr 25, 2011 at 7:10 PM, Skirmantas Kligys skirmantas.kli...@gmail.com wrote: I expected to be able to do what SAX does in Java, i.e. to avoid loading the whole 2 gigabytes into memory. For warm-up, I wrote an iteratee to count lines in the file, and it does load the whole file into memory! After profiling, I see that the problem was Data.Enumerator.Text.utf8, it allocates up to 60 megabytes when run on a 40 megabyte test file. It seems to me that this is a bug in enumerator's strict fold not being strict at all =). The current version 0.4.9.1 of Data.Enumerator.List.fold is -- | Consume the entire input stream with a strict left fold, one element -- at a time. -- -- Since: 0.4.8 fold :: Monad m = (b - a - b) - b - Iteratee a m b fold step = continue . loop where f = L.foldl' step loop acc stream = case stream of Chunks [] - continue (loop acc) Chunks xs - continue (loop (f acc xs)) EOF - yield acc EOF Note that the list fold is strict (f = Data.List.foldl' step), *however* the acc parameter of loop isn't strict at all! It just creates a big, fat thunk with references to all of you input =(. But the fix is extremely easy, just change the 'Chunks xs' line to Chunks xs - continue (loop $! f acc xs) Using only your iterLinesWc test with a 105 MiB file (a movie I had lying around), with enumerator's definition it takes 220 MiB of memory and 1.3~1.5 seconds according to +RTS -s. By doing only this very change above, it takes 2 MiB of memory (100x improvement :P) and 0.8~0.9 seconds. John Millikin, could you please apply the attached patch? =) Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] -- Extension for Pearls of Functional Algorithm Design by Richard Bird, 2010, page 25 #Haskell
-- Extension for Pearls of Functional Algorithm Design by Richard Bird, -- 2010, page 25 #Haskell -- This version assumes 3 disjoint ordered sets represented as lists. -- So either: xy XOR xy -- Since it uses lists it is no faster than the divide and conquer approach. -- I might try to convert this version to sorted arrays for -- O(log|X|+log|Y|+log|Z|) performance -- If I can figure out how to do it without suffering from indexitis. smallest3'' :: Ord a = Int - ([a], [a], [a]) - a smallest3'' k ([],[],ts) = ts !! k smallest3'' k (zs,[],[]) = zs !! k smallest3'' k ([],ws,[]) = ws !! k smallest3'' k ([],ws,ts) = smallest'' k (ws,ts) smallest3'' k (zs,[],ts) = smallest'' k (zs,ts) smallest3'' k (zs,ws,[]) = smallest'' k (zs,ws) smallest3'' k (zs,ws,ts) = case (ab, bc, ac) of ~~(True, True, True)- smallest3h'' k ((zs,p,ys),(ws,q),(ts,o,rs)) -- abc ~~(True, False, True) - smallest3h'' k ((zs,p,ys),(ts,o),(ws,q,us)) -- acb ~~(False, True, True) - smallest3h'' k ((ws,q,vs),(zs,p),(ts,o,rs)) -- bac ~~(False, True, False) - smallest3h'' k ((ws,q,vs),(ts,o),(zs,p,xs)) -- bca ~~(True, False, False) - smallest3h'' k ((ts,o,ss),(zs,p),(ws,q,us)) -- cab ~~(False, False, False) - smallest3h'' k ((ts,o,ss),(ws,q),(zs,p,xs)) -- cba where ~~p = (length zs) `div` 2 ~~q = (length ws) `div` 2 ~~o = (length ts) `div` 2 ~~(xs, a : ys) = splitAt p zs ~~(us, b : vs) = splitAt q ws ~~(rs, c : ss) = splitAt o ts ~~smallest3h'' k ((zs,p,ys),(ws,q),(ts,o,rs)) = case (k=p+q+o) of ~~(True)- smallest3'' k (zs,ws,rs) ~~(False) - smallest3'' (k-p-1) (ys,ws,ts) smallest'' :: Ord a = Int - ([a], [a]) - a smallest'' k ([],ws) = ws !! k smallest'' k (zs,[]) = zs !! k smallest'' k (zs,ws) = case (ab, k=p+q) of ~~(True, True) - smallest'' k (zs,us) ~~(True, False) - smallest''(k-p-1) (ys,ws) ~~(False, True) - smallest'' k (xs,ws) ~~(False, False)- smallest''(k-q-1) (zs,vs) where ~~p = (length zs) `div` 2 ~~q = (length ws) `div` 2 ~~(xs, a : ys) = splitAt p zs ~~(us, b : vs) = splitAt q ws ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] plugins and cabal build
Hi all, I'm experimenting with using the plugins package for yesod devel server. The basic approach is to use cabal for building the object files, and then load them with plugins. I can get everything to work when I compile with ghc --make, but I believe name mangling is getting in the way with the cabal build route. Can someone give some guidance on how to properly mangle the function names so that plugins can load them? Thanks, Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell from SML - referrential Transparency?!
On 26 April 2011 00:53, Ryan Ingram ryani.s...@gmail.com wrote: I've been working on Haskell for quite a while and it's not too often that a beginner shows me a new trick--this trick with trace seems really cool and I hadn't seen it before. f x | trace (f ++ show x) False = undefined f ... -- rest of regular definition Makes it really easy to add the trace and then later comment it out. One problem I always have with traces the usual way is that adding/removing them is kind of annoying--it can change the indentation of your code, etc. So this trick is really useful! Yes. It would be much better if trace were a primitive, whose semantics were to ignore the first argument and yield the second argument as a value. But these semantics would be changed by supplying an argument to the runtime (so you could turn tracing on-and-off between runs). Actually, this still isn't very convenient. Better would be to have another String argument - the trace key. Then the runtime argument would list those trace keys for which tracing should be performed. This way you never have to edit the code to add and remove tracing (though you may want to remove many trace statements when you are convinced the code is thoroughly debugged). -- Colin Adams Preston, Lancashire, ENGLAND () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
