- template-haskell - Haskell.org

not an instance of Lift?
by WANG Meng 05 Apr '05

05 Apr '05

Hi All, When I am trying to define the following program: test x = [|x|] y = test (Just True) The compiler will complain that Maybe Bool is not an instance of Lift. Is there any way to resolve this? Can I add instances to the class Lift? -W-M- @ @ | \_/

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RE: [Template-haskell] Ppr instance for Dec.
by Simon Peyton-Jones 04 Apr '05

04 Apr '05

It looks to me as if the where clause should be indented in all contexts. So I've added the 'nest nestDepth' in the defn of where_clause. Others feel free to make it look neater! Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Lemmih | Sent: 01 April 2005 14:19 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] Ppr instance for Dec. | | Greetings, | | I noticed this code in Language.Haskell.TH.Ppr: | | > ppr (ClassD ctxt c xs fds ds) = text "class" <+> pprCxt ctxt | > <+> ppr c <+> hsep (map ppr xs) <+> ppr fds | > $$ where_clause ds | > ppr (InstanceD ctxt i ds) = text "instance" <+> pprCxt ctxt <+> ppr i | > $$ where_clause ds | | shouldn't it be: | | > ppr (ClassD ctxt c xs fds ds) = text "class" <+> pprCxt ctxt | > <+> ppr c <+> hsep (map ppr xs) <+> ppr fds | > $$ nest nestDepth (where_clause ds) | > ppr (InstanceD ctxt i ds) = text "instance" <+> pprCxt ctxt <+> ppr i | > $$ nest nestDepth (where_clause ds) | | -- | Friendly, | Lemmih | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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RE: [Template-haskell] Splice Imports
by Simon Peyton-Jones 02 Apr '05

02 Apr '05

It should be, but it isn't (yet, anyway). It's one of those straightforward but tiresome jobs I have not gotten around to. I'll do it if enough TH users yell, loudly enough! Being able to add to exports seems desirable too, but requires some new syntax... Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Simon David Foster | Sent: 30 March 2005 18:58 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] Splice Imports | | Is it possible to splice imports in TH? It seems to be possible to | splice foreign imports, but is it possible to splice native module | imports, and if so how? | | Thanks, | | -Si. | | -- | Simon David Foster <s.d.f(a)btinternet.com> | | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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Reification of local variables
by WANG Meng 01 Apr '05

01 Apr '05

Hi, I am trying to write a function which does reification on its parameters. What I understand is that the reify below will get the type information of n available at the definition of fn. > fn n = $(do info <- (reify 'n)) But how about I define fn as > fn n = do info <- (reify 'n) then I splice $(fn x) somewhere else? Will the reify gets type information of x? Or something else? In the second case, GHC keep on complaining "`n' is not in the type environment at a reify" What is the reason for this? -W-M- @ @ | \_/

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Ppr instance for Dec.
by Lemmih 01 Apr '05

01 Apr '05

Greetings, I noticed this code in Language.Haskell.TH.Ppr: > ppr (ClassD ctxt c xs fds ds) = text "class" <+> pprCxt ctxt > <+> ppr c <+> hsep (map ppr xs) <+> ppr fds > $$ where_clause ds > ppr (InstanceD ctxt i ds) = text "instance" <+> pprCxt ctxt <+> ppr i > $$ where_clause ds shouldn't it be: > ppr (ClassD ctxt c xs fds ds) = text "class" <+> pprCxt ctxt > <+> ppr c <+> hsep (map ppr xs) <+> ppr fds > $$ nest nestDepth (where_clause ds) > ppr (InstanceD ctxt i ds) = text "instance" <+> pprCxt ctxt <+> ppr i > $$ nest nestDepth (where_clause ds) -- Friendly, Lemmih

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Any changes on splice syntax in GHC6.4
by WANG Meng 31 Mar '05

31 Mar '05

Hi All, Any of you knows whether there are any changes on splice syntax in GHC6.4? Prelude> $[|1|] <interactive>:1: parse error on input `$' What is the reason for this behaviour? -W-M- @ @ | \_/

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Splice Imports
by Simon David Foster 30 Mar '05

30 Mar '05

Is it possible to splice imports in TH? It seems to be possible to splice foreign imports, but is it possible to splice native module imports, and if so how? Thanks, -Si. -- Simon David Foster <s.d.f(a)btinternet.com>

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Final CFP: GPCE'05 -- Generative Programming and Component Engineering
by Eelco Visser 23 Mar '05

23 Mar '05

FINAL CALL for PAPERS and DEMOS preliminary announcement of WORKSHOPS and TUTORIALS ---------------------------------------------------------------------- 4th International Conference on Generative Programming and Component Engineering (GPCE'05) Sep 29 - Oct 1, 2005, Tallinn (Estonia) http://www.gpce.org/05 Sponsored by ACM SIGPLAN, in cooperation with ACM SIGSOFT co-located with ICFP'05 and TFP'05 ---------------------------------------------------------------------- Consult http://www.gpce.org/05 for UP-TO-DATE and DETAILED information, including the full text of the calls for PAPERS and DEMONSTRATIONS. ELECTRONIC SUBMISSION PAGE is active. FORTHCOMING: web pages for workshops and tutorials (mid April) ---------------------------------------------------------------------- IMPORTANT DATES * Apr 10, 2005: Submission of abstracts (only for papers) * Apr 15, 2005: Submission of papers and demos * May 30, 2005: Notification for papers and demos * Sep 27-28, 2005: GPCE workshops and tutorials * Sep 29 - Oct 1, 2005: GPCE papers and demos ---------------------------------------------------------------------- SCOPE. Generative and component approaches have the potential to revolutionize software development in a similar way as automation and components revolutionized manufacturing. Generative Programming (developing programs that synthesize other programs), Component Engineering (raising the level of modularization and analysis in application design), and Domain-Specific Languages (elevating program specifications to compact domain-specific notations that are easier to write and maintain) are key technologies for automating program development. GPCE arose as a joint conference, merging the conference on Generative and Component-Based Software Engineering (GCSE) and the workshop on Semantics, Applications, and Implementation of Program Generation (SAIG). The goal of GPCE is to provide a meeting place for researchers and practitioners interested in cutting edge approaches to software development. We aim to foster further cross-fertilization between the software engineering research community and the programming languages community, in addition to supporting the original research goals of both the GCSE and the SAIG communities. ---------------------------------------------------------------------- TOPICS. GPCE seeks contributions both in software engineering and in programming languages related (but not limited) to: * 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 and feature-oriented programming, - Intentional programming and multi-dimensional separation of concerns * Industrial applications ---------------------------------------------------------------------- CALL FOR PAPERS. Authors are invited to submit a title and abstract (by Apr 10) and a full paper (by Apr 15) reporting research results and/or experience related to the topics above. We especially encourage original high-quality reports on applications to real-world problems, relating ideas and concepts from several topics, or bridging the gap between theory and practice. Simultaneous submission to other venues and submission of previously published material are not allowed. Accepted papers will appear in the conference proceedings, to be published in Springer's LNCS series. SUBMISSION GUIDELINES. Electronic submission will be required (except by special arrangement with the PC chairs). Submissions must be in PDF, conform to the LNCS style, and be no longer than 15 PAGES. For formatting details see http://www.springer.de/comp/lncs/authors.html. ---------------------------------------------------------------------- TUTORIALS T1: Challenges and Best Practices of Generative Software Engineering in the Context of Large Complex Business Applications (Presenter: M.M.Davydov) T2: Implementing Domain-Specific Modelling Languages andGenerators (Presenters: R.Pohjonen and J-P.Tolvanen) T3: Multi-stage Programming in MetaOCaml (Presenters: W.Taha, C.Calcagno) WORKSHOPS W1: Second MetaOCaml Workshop (Organizers: K.Swadi, W.Taha) W2: Young Researchers Workshop (Organizers: D.R.Dechow, D.Foetsch, S.Kiebusch, S.Perugini, M.J.Rutherford, D.Shestakov) ---------------------------------------------------------------------- PROGRAM COMMITTEE Chairs: * Robert Glück (U. of Copenhagen) * Michael Lowry (NASA) Members: * Don Batory (U. of Texas, USA) * Ira Baxter (Semantic Designs) * Cristiano Calcagno (Imperial College) * Prem Devanbu (U. of California at Davis) * Ulrich Eisenecker (U. of Leipzig) * Tom Ellman (Vassar College) * Robert Filman (NASA) * Zhenjiang Hu (U. of Tokyo) * Patricia Johann (Rutgers U.) * John Launchbury (Galois) * Anne-Françoise Le Meur (U. of Sci. and Tech. Lille) * Hong Mei (Peking U.) * Nicolas Rouquette (NASA) * William Scherlis (CMU) * Yannis Smaragdakis (Georgia Inst. of Tech.) * Walid Taha (Rice U.) * Todd Veldhuizen (Chalmers U. of Tech.) ORGANIZING COMMITTEE General Chair * Eugenio Moggi (Genova U.) Publicity Chair * Eelco Visser (Utrecht U.) Workshops and Tutorials Chairs * Jeff Gray (U. of Alabama at Birmingham) * Andrew Malton (Waterloo U.) Local Arrangements Chair * Tarmo Uustalu (Inst. of Cybernetics, Tallinn) ----------------------------------------------------------------------

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declaration splicing
by WANG Meng 13 Mar '05

13 Mar '05

Hi All, I am trying to use template haskell to splice top level declarations. However, GHC complains "<interactive>:1: Variable not in scope: `splice'" May I know what is the problem here? Did I use the wrong syntax? -W-M- @ @ | \_/

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RE: [Template-haskell] Re: [Haskell] Proposal: Allow "\=" for field update in record update syntax
by Simon Peyton-Jones 08 Mar '05

08 Mar '05

To have what you want takes a syntactic extension to Haskell; TH requires '$' to indicate splices. You'd have to write something like $( [| name |] =:= val ) instead of name := val where (=:=) :: ExpQ -> a -> ExpQ You can do that today, but I guess you won't find it as convenient. It's very hard to know where to stop when adding syntax; and the record design space is particularly complicated (there have been many proposals, all with different relative merits). And defining new syntax often makes some existing programs stop working; in this case, ones that use ":=" as a data constructor. Simon | -----Original Message----- | From: S. Alexander Jacobson [mailto:alex@alexjacobson.com] | Sent: 07 March 2005 16:46 | To: Simon Peyton-Jones | Cc: template-haskell(a)haskell.org; Sander Evers | Subject: RE: [Template-haskell] Re: [Haskell] Proposal: Allow "\=" for field update in record update | syntax | | Most generally, I use records all over the place in my code (is this | bad style?), and the current syntax for record update is really | unwieldy. | | I'd like some way to have operators like (:=) and (:\=) for record | update. I don't yet know TemplateHaskell so I don't know how you | define functions in it, but I would like some way to write: | | name := val = \rec-> rec { name = val} | name :\= fn = \rec -> rec { name = fn $ name rec} | | And I would like to be able to use these operators as Sander Evers | showed: | | data Country = Country {capital :: City, ...} | data City = City {inhabitants :: Int, ...} | | birth_in_capital :: Country -> Country | birth_in_capital = capital :\= (inhabitants :\= (+1)) | | It would be even nicer if we could define the precedence of these | operators so that we could write the above | | birth_in_capital = capital :\= inhabitants :\= (+1) | | Though since haskell is usually prefix, perhaps it would be best to be | able to write it: | | birth_in_capital = (+1) :\= inhabitants :\= capital | | Note: It is entirely possible that this is a Haskell rather than a | template haskell issue. I don't know the border between the projects. | | -Alex- | | ______________________________________________________________ | S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com | | | | On Mon, 7 Mar 2005, Simon Peyton-Jones wrote: | | > What exactly is it that TH doesn't support, that you want? | > | > Simon | > | > | -----Original Message----- | > | From: template-haskell-bounces(a)haskell.org | > [mailto:template-haskell-bounces@haskell.org] On | > | Behalf Of S. Alexander Jacobson | > | Sent: 28 February 2005 10:32 | > | To: Sander Evers; template-haskell(a)haskell.org | > | Subject: [Template-haskell] Re: [Haskell] Proposal: Allow "\=" for | > field update in record update syntax | > | | > | Since operators can't start with a ':', is there an in-principle | > | reason TH does not support : operators? The syntax below would be | > | really nice to have. | > | | > | | > | | > | On Fri, 18 Feb 2005, Sander Evers wrote: | > | | > | > | > | >> Then we could have e.g. (:=) and (:\=) and end up with a | > | >> syntax that looks like this: | > | >> | > | >> rec // field :\= fn . field2 := val | > | >> | > | >> And that is BETTER than the Haskell syntax that I originally | > proposed. | > | > | > | > This syntax is also nice for composition of update functions, which | > is useful | > | > with nested records: | > | > | > | > data Country = Country {capital :: City, ...} | > | > data City = City {inhabitants :: Int, ...} | > | > | > | > birth_in_capital :: Country -> Country | > | > birth_in_capital = capital :\= (inhabitants :\= (+1)) | > | > | > | > This also shows that it would be useful to make :\= associate to the | > right. | > | > | > | | > | ______________________________________________________________ | > | S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com | > | _______________________________________________ | > | template-haskell mailing list | > | template-haskell(a)haskell.org | > | http://www.haskell.org/mailman/listinfo/template-haskell | >

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