[Haskell-cafe] Linking against Sqlite3 on Windows problem
Hi all! I created simple application, which uses sqlite3 as it's datastore back-end. I faced no problems when building and running it on Linux, but after I tried to build it on Windows, I see weird linking error: Linking dist\build\hnotes\hnotes.exe ... C:\Documents and Settings\Admin\Application Data\cabal\sqlite-0.5.2.2\ghc-7.0.4/libHSsqlite-0.5.2.2. a(sqlite3-local.o):sqlite3-local.c:(.text+0x21): undefined reference to `sqlite3_temp_directory' C:\Documents and Settings\Admin\Application Data\cabal\sqlite-0.5.2.2\ghc-7.0.4/libHSsqlite-0.5.2.2. a(sqlite3-local.o):sqlite3-local.c:(.text+0x40): undefined reference to `sqlite3_temp_directory' collect2: v ld 1 cabal.EXE: Error: some packages failed to install: hnotes-0.1 failed during the building phase. The exception was: ExitFailure 1 What may be wrong there? I suspect that qalite3.dll has to be added to linking stage, but have no idea how to do that. Adding --extra-lib-dirs=path-to-sqlite-dll doesn't help either (perhaps because I need to update my cabal file somehow, to support this?). Thank you for the help! -- Eugene N Dzhurinsky pgpQJzjGTBAjt.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] sample terms and interpreting program output from Tc Monad
[Sorry, I forgot to reply to the list.] Hi. I understand these to be Rank 0 terms: (\(x::Int) . x) (0 :: Int) :: (forall. Int) -- value (\(x::Int). x) :: (forall. Int - Int) Yes. (\(x::a). x) :: (forall. a - a) Although the program prints forall, the absence of a type variable indicates Rank 0, correct? It's a bit unclear what you mean, and the prototype implementation you seem to be using deviates from Haskell conventions here. The prototype checker sees a as a type constant here, so it plays the same role as Int before. In particular, a isn't a type variable, and there's no quantification. I understand these to be Rank 1 terms: (\x. x) :: (forall a. a - a) -- This is not the same as the third example above, right? This one identifies the type variable a, the one above does not. Also, there's no explicit annotation, it's inferred. The implementation indeed considers them to be different. Before a was a concrete type, and the function was the monomorphic identity function on that type. Now, a is a type variable, and the function is the polymorphic identity function. [...] I understand these to be Rank 2 terms: (\(x::(forall a. a)). 0) :: (forall. (forall a. a) - Int) The explicit forall annotation on the bound and binding variable x causes the program to infer a Rank 2 polytype as indicated by the - Int following the (forall a. a), while noting the absence of a type variable following the left-most forall printed by the program, correct? Your description here is a bit strange. It's a rank-2 type because there's a rank-1 type occurring to the left of the function arrow. (\(x::(forall a. a - a)). x) :: (forall b. (forall a. a - a) - b - b) Also Rank 2, only one arrow to the right of (forall a. a - a) counts. It's rank 2, yes. I'm not sure what you mean here by saying that only one arrow counts. The universal quantifier on type variable b ranges over the type variable a, correct? No. The universal quantifier ranges over all (mono)types. I understand this to be a Rank 3 term: (\(f::(forall a. a - a)). \(x::(forall b. b)). f (f x)) :: (forall c. (forall a. a - a) - (forall b. b) - c) No, this is still rank 2. It uses two rank 1 types as function arguments. For it to be rank 3, it'd have to use a rank 2 type in the argument position of a function type. Note that the function arrow associates to the right: forall c. (forall a. a - a) - ((forall b. b) - c) -- rank 2 (forall c. ((forall a. a - a) - (forall b. b)) - c) -- rank 3 The arrows to the right of the universally quantified a and b expressions qualify this as Rank 3. No, you seem to be applying a wrong definition of rank. The correct definition is given in Section 3.1 of the paper. Here's how you can derive the type above as a sigma_2: sigma_2 ~ forall c. sigma_2 ~ forall c. sigma_1 - sigma_2 ~ forall c. sigma_1 - sigma_1 - sigma_2 ~ forall c. sigma_1 - sigma_1 - sigma_1 ~ forall c. sigma_1 - sigma_1 - sigma_0 ~ forall c. sigma_1 - sigma_1 - c ~ forall c. (forall a. sigma_1) - sigma_1 - c ~ forall c. (forall a. sigma_0) - sigma_1 - c ~ forall c. (forall a. tau - tau) - sigma_1 - c ~ forall c. (forall a. a - a) - sigma_1 - c ~ forall c. (forall a. a - a) - (forall b. sigma_1) - c ~ forall c. (forall a. a - a) - (forall b. sigma_0) - c ~ forall c. (forall a. a - a) - (forall b. b) - c Type variable c ranges over type variables a and b, correct? No. Each of the type variables ranges over all (mono)types. (Or do you mean what the scope of c is? If so, then the scope of c is the complete type signature.) Cheers, Andres -- Andres Löh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANNOUNCE: control-monad-loop 0.1
* Joey Adams joeyadams3.14...@gmail.com [2012-07-09 01:38:06-0400] This package provides imperative-style loops supporting continue and break. For example: import Control.Monad import Control.Monad.IO.Class import Control.Monad.Trans.Loop import Control.Monad.Trans.Class main :: IO () main = foreach [0..] $ \i - foreach [0..] $ \j - do when (j == 0) $ continue-- skip to next iteration when (j = 5) $ exit-- exit the loop when (i = 5) $ lift exit -- exit the outer loop by calling 'exit' in the parent monad liftIO $ print (i, j) Very nice! Here's a patch to generalize foreach to any Foldable: https://github.com/joeyadams/haskell-control-monad-loop/pull/1 Also, it's not obvious how your tests work. Please consider using HUnit and test-framework (or similar) to organize them. -- Roman I. Cheplyaka :: http://ro-che.info/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Best way to build a GHC backend?
On Sun, Jul 08, 2012 at 09:21:08AM -0600, Jonathan Geddes wrote: I agree that the Raison d'être for a .NET or JVM backend is interop. Perhaps that's not worth the effort of an entirely new backend. JavaScript is a different beast, however. I said before: From my point of view, languages that cannot run on one of the 3 aforementioned platforms will become irrelevant. (with the exception of C, of course). I'll take that one step further and say that for web applications it is becoming increasingly difficult to justify using a language that WILL NOT run both client and server. JavaScript (with NodeJS), Clojure (with ClojureScript), and Dart are just a few examples. I really believe that with a solid JavaScript backend, Haskell would be an ideal web application language. Am I alone in that belief? What can I do to get the ball rolling on that? I should point out that the ball already IS rolling -- ranging from EDSLs that compile to JavaScript [1,2] to macro systems [3] to more serious full-featured efforts [4,5]. There's even a wiki page listing all these and more [6]. The yesod developers share your view that Haskell would benefit from some sort of JavaScript backend; see [7] as well as the ensuing discussion on Reddit [8]. See also Elm [9], which compiles to HTML+CSS+JavaScript and has some Haskell integration [10]. Rather than trying to start yet another effort, what about contributing to one of these ongoing ones? -Brent [1] http://www.ittc.ku.edu/csdlblog/?p=88 [2] http://www.ittc.ku.edu/csdl/fpg/node/125 [3] http://www.haskell.org/haskellwiki/JMacro [4] http://uu-computerscience.github.com/uhc-js/ [5] https://github.com/ghcjs/ghcjs [6] http://www.haskell.org/haskellwiki/The_JavaScript_Problem [7] http://www.yesodweb.com/blog/2012/04/client-side [8] http://www.reddit.com/r/haskell/comments/sm72n/client_side_yesod_an_frpinspired_approach/ [9] http://elm-lang.org/ [10] http://www.reddit.com/r/haskell/comments/uugne/announcing_elm_02_haskell_integration_yesod/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] combining predicates, noob question
On Sat, Jul 07, 2012 at 09:42:01PM -0300, Sebastián Krynski wrote: Ok , thanks for the answers, I understand now what liftM2 does. In this case would it be silly to use combinerPred (and maybe a newType Predicate a = a - Bool) for the sake of readability or shoud I stick with a - Bool and liftM2? No, not silly. Use whatever you find most readable. -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Implementors' Workshop talk proposals due in one week!
Reminder. The deadline is end-of-day this Tuesday. On Tue, Jul 3, 2012 at 7:17 AM, Johan Tibell johan.tib...@gmail.com wrote: Call for Talks ACM SIGPLAN Haskell Implementors' Workshop http://haskell.org/haskellwiki/HaskellImplementorsWorkshop/2012 Copenhagen, Denmark, September 14th, 2012 The workshop will be held in conjunction with ICFP 2012 http://www.icfpconference.org/icfp2012/ Important dates Proposal Deadline: 10th July 2012 Notification: 27th July 2012 Workshop: 14th September 2012 The Haskell Implementors' Workshop is to be held alongside ICFP 2012 this year in Copenhagen, Denmark. There will be no proceedings; it is an informal gathering of people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure. This relatively new workshop reflects the growth of the user community: there is a clear need for a well-supported tool chain for the development, distribution, deployment, and configuration of Haskell software. The aim is for this workshop to give the people involved with building the infrastructure behind this ecosystem an opportunity to bat around ideas, share experiences, and ask for feedback from fellow experts. We intend the workshop to have an informal and interactive feel, with a flexible timetable and plenty of room for ad-hoc discussion, demos, and impromptu short talks. Scope and target audience - It is important to distinguish the Haskell Implementors' Workshop from the Haskell Symposium which is also co-located with ICFP 2012. The Haskell Symposium is for the publication of Haskell-related research. In contrast, the Haskell Implementors' Workshop will have no proceedings -- although we will aim to make talk videos, slides and presented data available with the consent of the speakers. In the Haskell Implementors' Workshop, we hope to study the underlying technology. We want to bring together anyone interested in the nitty-gritty details behind turning plain-text source code into a deployed product. Having said that, members of the wider Haskell community are more than welcome to attend the workshop -- we need your feedback to keep the Haskell ecosystem thriving. The scope covers any of the following topics. There may be some topics that people feel we've missed, so by all means submit a proposal even if it doesn't fit exactly into one of these buckets: * Compilation techniques * Language features and extensions * Type system implementation * Concurrency and parallelism: language design and implementation * Performance, optimisation and benchmarking * Virtual machines and run-time systems * Libraries and tools for development or deployment Talks - At this stage we would like to invite proposals from potential speakers for a relatively short talk. We are aiming for 20 minute talks with 10 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Please submit a talk title and abstract of no more than 200 words to: johan.tib...@gmail.com We will also have a lightning talks session which will be organised on the day. These talks will be 2-10 minutes, depending on available time. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators. Organisers -- * Lennart Augustsson (Standard Chartered Bank) * Manuel M T Chakravarty (University of New South Wales) * Gregory Collins - co-chair (Google) * Simon Marlow (Microsoft Research) * David Terei(Stanford University) * Johan Tibell - co-chair(Google) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Best way to build a GHC backend?
Thanks for all the Info, Brent! I wasn't aware of many of those projects. I agree that contributing to an existing project is a better idea than doing something new. I suppose I was hoping there would be an official GHC JavaScript backend so that it would be clear which of the efforts to contribute to (and use). -J Arthur On Mon, Jul 9, 2012 at 8:38 AM, Brent Yorgey byor...@seas.upenn.edu wrote: On Sun, Jul 08, 2012 at 09:21:08AM -0600, Jonathan Geddes wrote: I agree that the Raison d'être for a .NET or JVM backend is interop. Perhaps that's not worth the effort of an entirely new backend. JavaScript is a different beast, however. I said before: From my point of view, languages that cannot run on one of the 3 aforementioned platforms will become irrelevant. (with the exception of C, of course). I'll take that one step further and say that for web applications it is becoming increasingly difficult to justify using a language that WILL NOT run both client and server. JavaScript (with NodeJS), Clojure (with ClojureScript), and Dart are just a few examples. I really believe that with a solid JavaScript backend, Haskell would be an ideal web application language. Am I alone in that belief? What can I do to get the ball rolling on that? I should point out that the ball already IS rolling -- ranging from EDSLs that compile to JavaScript [1,2] to macro systems [3] to more serious full-featured efforts [4,5]. There's even a wiki page listing all these and more [6]. The yesod developers share your view that Haskell would benefit from some sort of JavaScript backend; see [7] as well as the ensuing discussion on Reddit [8]. See also Elm [9], which compiles to HTML+CSS+JavaScript and has some Haskell integration [10]. Rather than trying to start yet another effort, what about contributing to one of these ongoing ones? -Brent [1] http://www.ittc.ku.edu/csdlblog/?p=88 [2] http://www.ittc.ku.edu/csdl/fpg/node/125 [3] http://www.haskell.org/haskellwiki/JMacro [4] http://uu-computerscience.github.com/uhc-js/ [5] https://github.com/ghcjs/ghcjs [6] http://www.haskell.org/haskellwiki/The_JavaScript_Problem [7] http://www.yesodweb.com/blog/2012/04/client-side [8] http://www.reddit.com/r/haskell/comments/sm72n/client_side_yesod_an_frpinspired_approach/ [9] http://elm-lang.org/ [10] http://www.reddit.com/r/haskell/comments/uugne/announcing_elm_02_haskell_integration_yesod/ ___ 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] Best way to build a GHC backend?
On 9 July 2012 15:38, Brent Yorgey byor...@seas.upenn.edu wrote: I should point out that the ball already IS rolling -- ranging from EDSLs that compile to JavaScript [1,2] to macro systems [3] to more serious full-featured efforts [4,5]. Also, a JavaScript backend has recently been developed for Clean, the other major lazy functional language. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] combining predicates, noob question
You can still use the monadic combinators, with the price of wrapping and
unwrapping in case of newtype.
newtype P a = P {unP :: a - Bool}
liftM2'P :: (Bool - Bool - Bool) - P a - P a - P a
liftM2'P op = (P .) . on (liftM2 op) unP
paolino
2012/7/8 Sebastián Krynski skryn...@gmail.com
Ok , thanks for the answers, I understand now what liftM2 does.
In this case would it be silly to use combinerPred (and maybe a newType
Predicate a = a - Bool) for the sake of readability or shoud I stick with
a - Bool and liftM2?
thanks, Sebastián
2012/7/6 Brent Yorgey byor...@seas.upenn.edu
On Fri, Jul 06, 2012 at 03:17:54PM -0300, Felipe Almeida Lessa wrote:
On Fri, Jul 6, 2012 at 2:11 PM, Sebastián Krynski skryn...@gmail.com
wrote:
As I was using predicates (a - bool) , it appeared the need for
combining
them with a boolean operator (bool - bool - bool) in order to get
a new
predicate
combining the previous two. So I wrote my function combinerPred (see
code
below). While I think this is JUST ok, i'm feeling a monad in the air.
So.. where is the monad?
combinerPred :: (a - Bool) - (a - Bool) - (Bool - Bool -
Bool) -
(a - Bool)
combinerPred pred1 pred2 op = \x - op (pred1 x) (pred2 x)
That's the `(-) a` monad:
import Control.Applicative
combinerPred :: (a - Bool) - (a - Bool) - (Bool - Bool -
Bool) - (a - Bool)
combinerPred pred1 pred2 op = op $ pred1 * pred2
By the way, I find it more natural to make 'op' the first argument,
because it is more useful to partially apply combinerPred to an
operation that it is to some predicates. Also, in that case
combinerPred is simply liftA2:
import Control.Applicative
combinerPred :: (Bool - Bool - Bool) - (a - Bool) - (a - Bool) -
(a - Bool)
combinerPred = liftA2
-Brent
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[Haskell-cafe] Sifflet type checker [from Re: [Haskell] ANNOUNCE: Sifflet visual programming language, release 2.0.0.0]
On 2012-Jul-07, Henning Thielemann wrote: On Thu, 5 Jul 2012, gdwe...@iue.edu wrote: Sifflet and sifflet-lib 2.0.0.0, now available on Hackage! This version introduces a type checker and partial support for higher order functions in Sifflet, the visual, functional programming language and support system for students learning about recursion. You have implemented your own type-checker, right? It is my code implementing the type checker from Simon Peyton-Jones's book The Implementation of Functional Programming Languages (1987). I plan to add a type-checker to our live-sequencer project. [1] So far I have thought about using the Helium type checker but I have not done it so far. If you want to make your type-checker useful for other projects, you may put it into a separate package without the hard to install dependencies on cairo and glib. I am very interested in receiving suggestions for modularizing my packages, and I thank you for this one. I should point out that the Sifflet type checker (unlike Helium's) is not a type checker for Haskell, or even a reduced version of Haskell, but for a very small language consisting of these expressions (from Language.Sifflet.Expr): data Expr = EUndefined | ESymbol Symbol | EBool Bool | EChar Char | ENumber Number | EString String | EIf Expr Expr Expr -- ^ if test branch1 branch2 | EList [Expr] | ELambda Symbol Expr | EApp Expr Expr -- ^ apply function to argument | ECall Symbol [Expr] -- ^ function name, arglist | EOp Operator Expr Expr -- ^ binary operator application | EGroup Expr-- ^ grouping parentheses deriving (Eq, Show) (there are some redundant variants there, because I designed Expr before thinking about type checking and then augmented it to add the type checker) and these types data Type = TypeVar TypeVarName -- named type variable | TypeCons TypeConsName [Type] -- constructed type deriving (Eq) Do you still think my type checker would be useful to you, or to Haskellers generally? [1] http://www.youtube.com/watch?v=sXywCHR9WwE Ah, I enjoyed the performance! Greg -- Gregory D. Weber, Ph. D.: Associate Professor of Informatics / \ Indiana University East 0 : Tel. (765) 973-8420; FAX (765) 973-8550 / \ http://mypage.iu.edu/~gdweber/ 1 [] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANNOUNCE: control-monad-loop 0.1
On Mon, Jul 9, 2012 at 8:28 AM, Roman Cheplyaka r...@ro-che.info wrote: Very nice! Here's a patch to generalize foreach to any Foldable: https://github.com/joeyadams/haskell-control-monad-loop/pull/1 Thanks for the patch! I merged it, but I plan to wait a little while before uploading another release to Hackage. This changes the signature of an existing function, so I'll have to bump the major version number. Also, it's not obvious how your tests work. Please consider using HUnit and test-framework (or similar) to organize them. The tests currently aren't automated. It's hard to write an automated test to make sure a program doesn't leak. Not impossible (thanks to GHC.Stats), but hard. Thanks for pointing out test-framework, though. -Joey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Sifflet type checker
On Mon, 9 Jul 2012, gdwe...@iue.edu wrote: data Type = TypeVar TypeVarName -- named type variable | TypeCons TypeConsName [Type] -- constructed type deriving (Eq) Do you still think my type checker would be useful to you, or to Haskellers generally? I see. Then it is probably not very useful for me. :-( [1] http://www.youtube.com/watch?v=sXywCHR9WwE Ah, I enjoyed the performance! Nice to hear that you like it! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Linking against Sqlite3 on Windows problem
On Mon, Jul 9, 2012 at 3:56 AM, Eugene Dzhurinsky jdeve...@gmail.com wrote: Hi all! I created simple application, which uses sqlite3 as it's datastore back-end. I faced no problems when building and running it on Linux, but after I tried to build it on Windows, I see weird linking error: You could use the bundled sqlite3.c instead: cabal install --flags=builtin-sqlite3 Unfortunately, the sqlite3 package currently ships with a very old version of sqlite3.c (version 3.5.9). I submitted a bug report: https://github.com/GaloisInc/sqlite/issues/1 Until a fix is pushed, you can try downloading the latest sqlite3.c yourself, and placing it at sqlite3.6/sqlite3.c . I don't know if you will encounter any compatibility issues or not. Hope this helps, -Joey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
