- template-haskell - Haskell.org

splices in type signatures
by Frederik Eaton 15 Jun '06

15 Jun '06

Hello, Is it possible to have a TH splice in a type signature? It seems to generate a parse error, but I thought there might be another syntax that I'm not aware of. Thanks, Frederik -- http://ofb.net/~frederik/

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CFP: Partial Evaluation and Program Manipulation (PEPM'07)
by Eelco Visser 14 Jun '06

14 Jun '06

----------------------------------------------------------------------- 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. 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 webbased programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. ----------------------------------------------------------------------- Submission Categories, Guidelines, and Proceedings 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. We plan to publish the workshop proceedings in the ACM Digital Library (approval pending) 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 (IBM Research, Bangalore) * Eelco Visser (Utrecht University, The Netherlands) Program Committee Members (under construction): * 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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functions and quasi-quote
by Creighton Hogg 16 May '06

16 May '06

Hi, So I was playing with template Haskell earlier and there's something that I don't really understand. I can do something such as [|(+)|] just fine, but what I *want* is to do something like (\x -> [|x|]) (+) for example. (\x -> [|x|]) can be applied to numbers just fine, but not functions because it doesn't have an instance for Lift I'm just confused by this. Is there something I fundamentally don't understand about the Quasi monad?

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Type inference
by Oleg Mürk 25 Apr '06

25 Apr '06

Hello, I have the following problem. I'd like to infer types of local bindings using 'reify': ------------------------------------ testValue = let a = 10 in $(do VarI _ t _ _ <- reify 'a lift (pprint t) ) ------------------------------------- But this code prints only: ------------------------------------- *Debug> testValue "t_0" ------------------------------------- Is this intended behavior? Are there any workarounds? Things work fine if symbol is defined in another module. I do realise that in general $(...) may add additional constraints on local variables. OM

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Question about local bindings
by Andy Gill 18 Apr '06

18 Apr '06

Fellow Templaters, Why does test2 () = runQ [| foldr f z xs |] (f,z,xs) = undefined compile fine, but test2 () = runQ [| foldr f z xs |] where (f,z,xs) = undefined fail with this message: ./Language/Haskell/ER/Equation.hs:108:25: Can't splice the polymorphic local variable `f' In the first argument of `foldr', namely `f' In the first argument of `runQ', namely `[| foldr f z xs |]' In the definition of `test2': test2 () = runQ [| foldr f z xs |] where (f, z, xs) = undefined Andy Gill

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RE: [Template-haskell] quasi quotes and Q monad
by Simon Peyton-Jones 14 Apr '06

14 Apr '06

I've read your message, but I can't figure out what problem you are trying to solve. Can you give a small example that demonstrates it? Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Ch. A. Herrmann | Sent: 02 January 2006 16:17 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] quasi quotes and Q monad | | Dear TH experts, | | I have a problem concerning the interaction of quasi quotes and the | quotation monad. Assume a code generating function f (... -> Q Exp) | which is parameterized by a code generating function g (of type | Exp -> Q Exp, or(?) Q Exp -> Q Exp). | | Expressing the problem in the simplest form, the actual instance for g | is (\x -> [| h($x) |]), where h is a toplevel Haskell function working | on arbitrary types, and function f instantiates x | with an expression which consists just of a single variable (VarE). In | order to splice x in the code ($x), the type of x must be (Q Exp). The | reason for that, as mentioned in the 2002 paper | by Sheard and Peyton Jones "Template Metaprogramming for Haskell", is | that the computation of x must be able to access the Q monad. The place | inside f where the actual name for the variable x is generated, has | already access to the Q monad and the *result* of g is | embedded in this monad, no problem. However, I cannot figure out how | this monad can be passed as an *argument* to g and conceptually, there | is no justification to pass this monad: it is just an offspring version | of the one where the lexical scope of g belongs to. | | The value I want to pass for x is of type Exp. Of course, I could turn | this type into (Q Exp) by applying return, but this artificial instance | of the Q monad would come from nowhere, not being connected with the | regular instance used, e.g., for the fresh name generation. | | Especially, I have the following questions: | * Is there a simple solution to this problem? If so, please tell me and | forget about the following questions. | * Is the quasi quote mechanism at all appropriate for what I want to do | or should one better change to the concrete AST representation? That | | would be unfortunate because my aim is to develop Template Haskell | examples which demonstrate ease of use. | * If return is used to turn an expression into monadic form before | splicing, is it possible that | (a) the consistency of fresh name generation is lost, even if one | does the name generation for the spliced expression oneself, | (b) something else goes wrong? | | Many thanks in advance and a Happy New Year | -- | Christoph Herrmann | | | | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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RE: [Template-haskell] instance Show Info ?
by Simon Peyton-Jones 10 Apr '06

10 Apr '06

No very good reason. You can always use 'ppr'. Neverthless, since the rest of Exp is in Show, I'll add Info too. Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Dimitry Golubovsky | Sent: 05 April 2006 10:32 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] instance Show Info ? | | Why there isn't one? | | At least in "latest" (6.4.x), only instance Ppr Info shows up. | | It might be useful to be able to print raw results of reification. | | -- | Dimitry Golubovsky | | Anywhere on the Web

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RE: [Template-haskell] Renaming in pretty printer
by Simon Peyton-Jones 10 Apr '06

10 Apr '06

I've no idea. It certainly seems that Language.Haskell.TH.PprLib implements a pretty-printing Doc type that does renaming as it goes. I guess that he wanted to have shorter variable names. It's done using a state monad, which looks fragile to me: it appears to rely utterly on printing TH syntax trees with NameUs that do not involve shadowing; which is probably the case, but is not part of the specification. I'm not sure who wrote it: Don Stewart perhaps. Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Andy Gill | Sent: 28 March 2006 18:58 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] Renaming in pretty printer | | Template Haskell appears to be doing renaming during pretty printing. | Take this example, that both prints the AST directly, as well as | pretty printing. | | *Main> runQ ([| let x = 1 in x |]) >>= \x -> print (pprint x,x) | ("let x_0 = 1\n in x_0",LetE [ValD (VarP x_7) (NormalB (LitE | (IntegerL 1))) []] (VarE x_7)) | | The var x has name x_7 in the AST, but x_0 in the pretty printed | version. | | Can someone comment on why this is done? | | Andy Gill

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instance Show Info ?
by Dimitry Golubovsky 05 Apr '06

05 Apr '06

Why there isn't one? At least in "latest" (6.4.x), only instance Ppr Info shows up. It might be useful to be able to print raw results of reification. -- Dimitry Golubovsky Anywhere on the Web

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Renaming in pretty printer
by Andy Gill 28 Mar '06

28 Mar '06

Template Haskell appears to be doing renaming during pretty printing. Take this example, that both prints the AST directly, as well as pretty printing. *Main> runQ ([| let x = 1 in x |]) >>= \x -> print (pprint x,x) ("let x_0 = 1\n in x_0",LetE [ValD (VarP x_7) (NormalB (LitE (IntegerL 1))) []] (VarE x_7)) The var x has name x_7 in the AST, but x_0 in the pretty printed version. Can someone comment on why this is done? Andy Gill

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