- template-haskell - Haskell.org

Type variables within type quasiquotes
by Alfonso Acosta 21 Feb '07

21 Feb '07

Hi, Contrary to what's stated in GHC's 6.6 user's guide (http://www.haskell.org/ghc/docs/6.6/html/users_guide/template-haskell.html ) type quasiquotes seem to work just fine when type variables are not used (i.e. things such as [t| Bool |]). But unfortunately GHC complains when I make use of type variables [t| Maybe a |] leads to "Not in scope: type variable `a' " Am I doing something wrong or did I run into one of the reasons why the guide says that type quasi-quotes are not implemented? Thanks in advance, Alfonso Acosta

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GPCE'07: Calls for Tutorials/Workshops
by Emir Pasalic 08 Feb '07

08 Feb '07

CALL FOR TUTORIAL PROPOSALS Sixth International Conference on Generative Programming and Component Engineering (GPCE'07) October 1-3, 2007 in Salzburg, Austria (co-located with ESWEEK'07). http://www.gpce.org/07 Important Dates * Submission deadline for tutorial proposals: Friday March 16th * Date for notification of acceptance: Monday April 9th Note that this call is for tutorial organizers; tutorial registration is with the conference registration. Overview Proposals for high-quality tutorials in all areas of generative programming and component-based development, from academic research to industrial applications, are solicited. Tutorial levels may be introductory, intermediate, or advanced. A tutorial's purpose is to give a deeper insight into an area than a conventional lecture. Tutorials extend over a half or a full day. This gives the speaker the possibility to select a proper length for their tutorial. The topic of a tutorial can come from a truly broad spectrum. Any interesting theme included but not restricted to the following topic list is welcome: * Generative programming * Reuse, meta-programming, partial evaluation, multi-stage and multi-level languages, step-wise refinement * Semantics, type systems, symbolic computation, linking and explicit substitution, in-lining and macros, templates, program transformation * Runtime code generation, compilation, active libraries, synthesis from specifications, development methods, generation of non-code artifacts, formal methods, reflection * Generative techniques for * Product lines and architectures * Embedded systems * Model-driven architecture * Component-based software engineering * Reuse, distributed platforms, distributed systems, evolution, analysis and design patterns, development methods, formal methods * Integration of generative and component-based approaches * Domain engineering and domain analysis * Domain-specific languages (DSLs) including visual and UML-based DSLs * Separation of concerns * Aspect-oriented programming and feature-oriented programming, * Intentional programming and multi-dimensional separation of concerns * Industrial applications However, you should keep in mind that a tutorial must be expected to attract a reasonable number of participants. This is most likely the case if the topic is new or relevant to a broad community. If you have deep experience in a GPCE topic area, from which others could benefit, please consider submitting a proposal. Submission Format, Recommendations, and Process For details on the submission format, recommendations for submissions, and an overview of the submission process, please see the complete GPCE'07 call for tutorial proposals at: http://www.gpce.org/07 Follow the "Tutorials" link in the left sidebar. Tutorial Chair Ulrik P. Schultz (University of Southern Denmark, Denmark) For additional information, clarification, or questions please feel free to contact the Tutorial Chair at tutorials07(a)gpce.org CALL FOR WORKSHOP PROPOSALS Sixth International Conference on Generative Programming and Component Engineering (GPCE'07) October 1-3, 2007 in Salzburg, Austria (co-located with ESWEEK'07). http://www.gpce.org/07 Important Dates * Submission deadline for workshop proposals: Friday March 16th * Date for notification of acceptance: Monday April 9th Note that this call is for workshop organizers; a later call will occur for workshop contributions. Overview GPCE workshops provide intensive collaborative environments where generative and component technology researchers and practitioners meet to discuss and solve challenging problems facing the field. We encourage proposals for innovative, well-focused workshops on a broad spectrum of component engineering and generative programming topics. All topics related to the theme of the conference are potential candidates for workshops. Workshops typically fall into the following categories: * A workshop may address a specific sub-area of generative and component technology in depth. * A workshop may cover areas that cross the borders of several sub areas. Workshops that cross the borders of the formal and the applied areas is one example. * A workshop may also cross the border to other technologies or software engineering fields, e.g. development processes. * A workshop may focus on the application and deployment of generative and/or component technology in areas such as telecommunications, mobile computing or real-time systems. Workshops reporting on industrial experiences are particularly welcome. Workshop topics are by no means limited to the categories mentioned above. However, in each case, the proposed area is supposed to have enough impetus to yield new results that can be considered important and worth more detailed investigation. Submission Format, Recommendations, and Process For details on the submission format, recommendations for submissions, and an overview of the submission process, please see the complete GPCE'07 call for workshop proposals at: http://www.gpce.org/07 Follow the "Workshops" link in the left sidebar. Workshop Chair Ulrik P. Schultz (University of Southern Denmark, Denmark) For additional information, clarification, or questions please feel free to contact the Workshop Chair at workshops07(a)gpce.org.

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Third CFP: Partial Evaluation and Program Manipulation (PEPM'07)
by Eelco Visser 03 Oct '06

03 Oct '06

---------------------------------------------------------------------- electronic submission is open http://www.easychair.org/PEPM2007 ---------------------------------------------------------------------- Third Call For Papers ACM SIGPLAN 2007 Workshop on PARTIAL EVALUATION AND PROGRAM MANIPULATION (PEPM'07) Nice, France January 15-16, 2007 (Co-located with POPL 2007) http://www.program-transformation.org/PEPM07 ---------------------------------------------------------------------- The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the areas of program manipulation, partial evaluation, and program generation. PEPM focuses on techniques, theory, tools, and applications of analysis and manipulation of programs. The 2007 PEPM workshop will be based on a broad interpretation of semantics-based program manipulation and continue last year's successful effort to expand the scope of PEPM significantly beyond the traditionally covered areas of partial evaluation and specialization and include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule- based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to reach out to practitioners, a separate category of tool demonstration papers will be solicited. ---------------------------------------------------------------------- Topics of interest for PEPM'07 include, but are not limited to: + Program and model manipulation techniques such as transformations driven by rules, patterns, or analyses, partial evaluation, specialization, slicing, symbolic execution, refactoring, aspect weaving, decompilation, and obfuscation. + Program analysis techniques that are used to drive program/model manipulation such as abstract interpretation, static analysis, binding-time analysis, dynamic analysis, constraint solving, and type systems. + Analysis and transformation for programs/models with advanced features such as objects, generics, ownership types, aspects, reflection, XML type systems, component frameworks, and middleware. + Techniques that treat programs/models as data objects including meta-programming, generative programming, staged computation, and model-driven program generation and transformation. + Application of the above techniques including experimental studies, engineering needed for scalability, and benchmarking. Examples of application domains include legacy program understanding and transformation, domain-specific language implementations, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. We especially encourage papers that break new ground including descriptions of how program/model manipulation tools can be integrated into realistic software development processes, descriptions of robust tools capable of effectively handling realistic applications, and new areas of application such as rapidly evolving systems, distributed and web-based programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. ---------------------------------------------------------------------- Submission Categories and Guidelines Regular research papers must not exceed 10 pages in ACM Proceedings style. Tool demonstration papers must not exceed 4 pages in ACM Proceedings style, and authors will be expected to present a live demonstration of the described tool at the workshop. Suggested topics, evaluation criteria, and writing guidelines for both research tool demonstration papers will be made available on the PEPM'07 web site. Papers should be submitted electronically via the workshop web site. The workshop proceedings will be published in the ACM Digital Library and selected papers will be invited for a journal special issue dedicated to PEPM'07. ---------------------------------------------------------------------- Important Dates + Abstracts due: October 18, 2006 + Submission: October 20, 2006 + Notification: December 1, 2006 + Camera-ready: December 18, 2006 + Workshop: January 15-16, 2007 ----------------------------------------------------------------------- Program Chairs * G. Ramalingam (Microsoft Research, Bangalore) * Eelco Visser (Delft University of Technology, The Netherlands) Program Committee Members * Ras Bodik (University of California, Berkeley, USA) * Albert Cohen (INRIA, France) * Jim Cordy (Queen's University, Canada) * Martin Erwig (Oregon State University, USA) * Bernd Fischer (University of Southampton, UK) * John Hatcliff (Kansas State University, USA) * Jan Heering (CWI, The Netherlands) * Dan Grossman (University of Washington, USA) * Annie Liu (State University of New York at Stony Brook, USA) * Jacques Noy� (�cole des Mines de Nantes/INRIA, France) * German Puebla (Technical University of Madrid, Spain) * Peter Sestoft (Royal Veterinary and Agricultural University, Denmark) * Yannis Smaragdakis (Georgia Tech, Atlanta, USA) * Walid Taha (Rice University, Houston, USA) -----------------------------------------------------------------------

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Second CFP: Partial Evaluation and Program Manipulation (PEPM'07)
by Eelco Visser 12 Sep '06

12 Sep '06

---------------------------------------------------------------------- Second Call For Papers ACM SIGPLAN 2007 Workshop on PARTIAL EVALUATION AND PROGRAM MANIPULATION (PEPM'07) Nice, France January 15-16, 2007 (Co-located with POPL 2007) http://www.program-transformation.org/PEPM07 ---------------------------------------------------------------------- The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the areas of program manipulation, partial evaluation, and program generation. PEPM focuses on techniques, theory, tools, and applications of analysis and manipulation of programs. The 2007 PEPM workshop will be based on a broad interpretation of semantics-based program manipulation and continue last year's successful effort to expand the scope of PEPM significantly beyond the traditionally covered areas of partial evaluation and specialization and include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule- based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to reach out to practitioners, a separate category of tool demonstration papers will be solicited. ---------------------------------------------------------------------- Topics of interest for PEPM'07 include, but are not limited to: + Program and model manipulation techniques such as transformations driven by rules, patterns, or analyses, partial evaluation, specialization, slicing, symbolic execution, refactoring, aspect weaving, decompilation, and obfuscation. + Program analysis techniques that are used to drive program/model manipulation such as abstract interpretation, static analysis, binding-time analysis, dynamic analysis, constraint solving, and type systems. + Analysis and transformation for programs/models with advanced features such as objects, generics, ownership types, aspects, reflection, XML type systems, component frameworks, and middleware. + Techniques that treat programs/models as data objects including meta-programming, generative programming, staged computation, and model-driven program generation and transformation. + Application of the above techniques including experimental studies, engineering needed for scalability, and benchmarking. Examples of application domains include legacy program understanding and transformation, domain-specific language implementations, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. We especially encourage papers that break new ground including descriptions of how program/model manipulation tools can be integrated into realistic software development processes, descriptions of robust tools capable of effectively handling realistic applications, and new areas of application such as rapidly evolving systems, distributed and web-based programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. ---------------------------------------------------------------------- Submission Categories and Guidelines Regular research papers must not exceed 10 pages in ACM Proceedings style. Tool demonstration papers must not exceed 4 pages in ACM Proceedings style, and authors will be expected to present a live demonstration of the described tool at the workshop. Suggested topics, evaluation criteria, and writing guidelines for both research tool demonstration papers will be made available on the PEPM'07 web site. Papers should be submitted electronically via the workshop web site. The workshop proceedings will be published in the ACM Digital Library and selected papers will be invited for a journal special issue dedicated to PEPM'07. ---------------------------------------------------------------------- Important Dates + Abstracts due: October 18, 2006 + Submission: October 20, 2006 + Notification: December 1, 2006 + Camera-ready: December 18, 2006 + Workshop: January 15-16, 2007 ----------------------------------------------------------------------- Program Chairs * G. Ramalingam (Microsoft Research, Bangalore) * Eelco Visser (Delft University of Technology, The Netherlands) Program Committee Members * Ras Bodik (University of California, Berkeley, USA) * Albert Cohen (INRIA, France) * Jim Cordy (Queen's University, Canada) * Martin Erwig (Oregon State University, USA) * Bernd Fischer (University of Southampton, UK) * John Hatcliff (Kansas State University, USA) * Jan Heering (CWI, The Netherlands) * Dan Grossman (University of Washington, USA) * Annie Liu (State University of New York at Stony Brook, USA) * Jacques Noyé (École des Mines de Nantes/INRIA, France) * German Puebla (Technical University of Madrid, Spain) * Peter Sestoft (Royal Veterinary and Agricultural University, Denmark) * Yannis Smaragdakis (Georgia Tech, Atlanta, USA) * Walid Taha (Rice University, Houston, USA) -----------------------------------------------------------------------

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automatic instances for pretty printing and parsing
by Johannes Waldmann 09 Sep '06

09 Sep '06

Dear all, I use Text.PrettyPrint.HughesPJ and Text.ParserCombinators.Parsec heavily so I made some DrIFT rules for deriving the "obvious" instances for class ToDoc a where toDoc :: a -> Doc class Reader a where readerPrec :: Int -> Parser a http://141.57.11.163/cgi-bin/cvsweb/drift/src/UserRuleToDoc.hs?rev=1.5 Still I'd like to avoid external preprocessors (for hygienic reasons, and because they do not seem to fit well with the Cabal model) so I'd like to investigate whether I could get the same effect with Template Haskell (in ghc) - and what this would cost. Perhaps someone has solved a similar problem before. On the other hand, HaXml does need DrIFT it seems. -- -- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 -- ---- http://www.imn.htwk-leipzig.de/~waldmann/ -------

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Small TH demo: generating instances
by Rene de Visser 02 Sep '06

02 Sep '06

I am hoping that this example is small, simple and well commented enough to help people generate instances with TH. The instance generation is used to create instances to render haskell code to TH code that generates the original haskell code. there is an example in Test.hs The instance generation function is in Base.hs. TH_Render.hs is where the instances are derived. 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M;W5T(@T*(" @(" @(" @(" @(" @(" @(" @(" @(" @(" @(" @(" @(&]T M:&5R=VES92 M/B B8G5I;&0B( T*(" @(" @(" @(" @(" @(" @(" @("TM M(&)U:6QD("=F=6YC3F%M92!P87)M,2!P87)M,B!P87)M,R N+BX-"B @(" @ M(" @(" @(" @(" @("!I;B!A<'!S12 D("AV87)%("0(a);6M.86UE(&AE861& M=6YC*3IF=6YC3F%M93IV87)S("TM('!U="!I="!A;&P@=&]G971H97(-"B @ M(" @(" @(" @(" M+2!E<75I=F%L96YT('1O("=F=6YC4W1R('=H97)E(&9U M;F-3='(@0T].5$%)3E,@=&AE(&YA;64@=&\@8F4@<F5T=7)N960-"B @(" @ M(" @(" @("!M86ME3F%M92!F=6YC4W1R(#T@*&%P<$4@*'9A<D4@*&UK3F%M M92 B;6M.86UE(BDI("AL:71%("0@4W1R:6YG3"!F=6YC4W1R*2D-"B @(" @ *(" @(" @(" -"@`` ` end begin 666 Test.hs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2 2

Fix pprinting global names
by Einar Karttunen 31 Aug '06

31 Aug '06

Hello The recent commit added package names to pprinting global names. The attached patch reverts that - which is nice for actually using the pprinted representation and agrees with the comments in the file. e.g. base:GHC.Show.Show -> GHC.Show.Show Patch attached. - Einar Karttunen

1 0

Tool to preprocess template haskell definitions?
by Einar Karttunen 31 Aug '06

31 Aug '06

Hello I remember someone having written a small utility to preprocess a Haskell source file with TH definitions and generate a new file with the TH bits replaced by their resulting slices. If anyone knows the utility or a way to do this pointers would be nice. I am trying to use Haddock to create documentation, but datatypes are created with TH... - Einar Karttunen

2 1

GADTs
by Ian Lynagh 15 Aug '06

15 Aug '06

Hi all, Currently we do not have GADT support in Template Haskell, but I need it for something I'm working on. The relevant datastructures currently look like this: data Dec = ... | DataD Cxt Name [Name] [Con] [Name] | ... data Con = NormalC Name [StrictType] | RecC Name [VarStrictType] | InfixC StrictType Name StrictType | ForallC [Name] Cxt Con I propose altering Dec thus: data Dec = ... | DataD Cxt Name [Name] Cons [Name] | ... (changing [Con] to Cons) and adding new datastructures: data Cons = NormalCons [Con] | GadtCons [GadtCon] deriving( Show, Eq ) data GadtCon = GadtC [Name] Cxt Name [StrictType] Type deriving( Show, Eq ) (this follows the style used to add pattern guards to the datastructures). Complete patches for GHC and the template-haskell library are at http://urchin.earth.li/~ian/th-gadts/ If you have any objections or comments then please let me know; otherwise I think it would be great to get this into GHC 6.6. Thanks Ian

5 13

Internal type consistency of quoted expressions
by Liyang HU 02 Aug '06

02 Aug '06

(oops. Sorry about the double-post. Sent it with a wrong From: line and it doesn't seem to have come through...) Hello all, Long story, but one thing after another led me to resort to TH as a means to (re-)implement Conor McBride's (applicative) idiom brackets[0], where: [[ g x0 x1 ... xn ]] expands to pure g <*> x0 <*> x1 <*> ... <*> xn (pure and <*> come from Control.Applicative.) While I can't use [[ and ]], I can define a CPP macro: #define II(e) $( idiom [| e |] ) where the idiom function does the above rewriting at compile time. II( ... ) looks acceptable as a replacement for [[ ... ]]. Good. (Just as well, since the type-level implementation of the iI Ii brackets given in [1] will no longer work as of GHC 6.5, but is used fairly extensively in the Epigram 2 source code...) Even though (g x0 x1 ... xn) won't typecheck outside of a quotation, I can nevertheless get away with [| g x0 x1 ... xn |] because it is /internally/ consistent. (Template Meta-programming for Haskell, §7.1 paragraph 3; figure 2, rule BRACKET.) Yesterday, Conor pointed out that the if and case constructs are pure 'things', and since my implementation of the above idiom function seemed capable of this sort of syntax mangling, why not treat them as one more case in the applicative/monadic idiom bracket. (I've always wanted monadic if and case expressions. Hurrah!) The idea being that: II( if c then t else e ) and II( case d of { ... } ) would expand to c >>= \ b -> if b then t else e and d >>= \ x -> case x of { ... } respectively. I'd already written some of this up, and just got around to implementing the changes earlier tonight, but I'm stumped by the internal type consistency restriction: c has type (Monad m => m Bool), which means [| if c then t else e |] isn't 'internally consistent'. With the case-expression, d has type (Monad m => m a); (x :: a); and the elided patterns in { ... } match values of type a. So [| case d of { ... } |] won't get past the supposed 'sanity check'[2] either. :( My current want-it-now 'solution' is to comment out the sole tcSimplifyBracket invocation in ghc/compiler/typecheck/TcSplice.lhs. Clearly this is the wrong approach, seeing as other people would like to use this too. (I presume this will do what I want. I'm still waiting for stage1 to finish building...) I guess a more constructive approach would be to hack in an alternative unchecked quotation bracket, [s| ... |] say ('s' stands for 'syntax'). If upstream is willing to consider such an extension, I'll get started... Any alternative suggestions before I do? :-/ Thanks for listening, /Liyang [0] http://cs.nott.ac.uk/~ctm/IdiomLite.pdf [1] http://cs.nott.ac.uk/~ctm/Idiom.pdf [2] I am sane, right? I mean, is there any other reason for the internal type-consistency check other than to detect /potential/ errors /earlier/?

3 2