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creating xml doc with haxml
by Taesch, Luc 23 May '01

23 May '01

i understand now how to filter existing xml doc with haxml. but what about creation from scratch ? if i have myCFel = mkElem "tag" [(literal "value")] myel is a CFilter, not an element so i i want to create a effective element ( to pass to putStrLn . render $ ppContent for instance), i should give it something to filter, like emptyContent = CString False "" to finally do myel = mylit emptyContent . are there any other way to use combinator for creating a structure ( as opposed to "operate on an existing structure")? thanks Luc This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. CREDIT SUISSE GROUP and each of its subsidiaries each reserve the right to monitor all e-mail communications through its networks. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorised to state them to be the views of any such entity. Unless otherwise stated, any pricing information given in this message is indicative only, is subject to change and does not constitute an offer to deal at any price quoted. Any reference to the terms of executed transactions should be treated as preliminary only and subject to our formal written confirmation.

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BAL paper available
by S.D.Mechveliani 23 May '01

23 May '01

Paper announcement ------------------ The file http://www.botik.ru/pub/local/Mechveliani/basAlgPropos/haskellInCA1.ps.zip contains more expanded explanations on the BAL (Basic Algebra Library) project (previous variant was haskellInCA.ps.zip). My real intention in whole this line of business was always not just to propose a standard but rather to discuss and to find, what may be an appropriate way to program mathematics in Haskell. The matter was always in parametric domains ... Whoever tried to program real CA in Haskell, would agree that such a problem exists. ----------------- Serge Mechveliani mechvel(a)botik.ru

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Tutor for Haskell is Wanted
by Jbkim1078＠aol.com 23 May '01

23 May '01

Hello, I am Yoon, a student of UNSW in Sydney,Australia. I am learning Haskell but need a lot of help for the course. Is there any way that I can get a private tutor? Thanks very much.

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RE: Haskell & .NET CLR
by Simon Peyton-Jones 23 May '01

23 May '01

| Are any of the various Haskell implm., e.g. ghc, being | targeted for the .NET CLR? Yes, we are, here in Cambridge. We've run some Haskell programs on the CLR already, but it's not nearly ready for release. Simon

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Re: Haskell & .NET CLR
by Bill Halchin 22 May '01

22 May '01

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Haskell & .NET CLR
by Bill Halchin 22 May '01

22 May '01

Hello, Are any of the various Haskell implm., e.g. ghc, being targeted for the .NET CLR? Also can anybody point in the direction of any projects to implement the .NET CLR on anything other than Win32 platforms, e.g. that evil Free Software Foundation :^)?? Let's make .NET open source! hehehehhee Regards, Bill Halchin _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com

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Re: Templates in FPL?
by cwitty＠newtonlabs.com 22 May '01

22 May '01

"D. Tweed" <tweed(a)cs.bris.ac.uk> writes: > In my experience the C++ idiom `you only pay for what you use' (==> > templates are essentially type-checked macros) and the fact most compilers > are evolved from C compilers makes working with templates a real pain in > practice. I'm not sure what you mean by type-checked here. Templates are not type-checked at definition time, but are type-checked when they are used; the same is true of ordinary macros. Carl Witty

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RE: Recursive types?
by David Bakin 22 May '01

22 May '01

Thank you. Now, on seeing your Tree example I tried to use it by defining height using structural recursion. But I couldn't find a valid syntax to pattern match - or otherwise define the function - on the type CT. Is there one? Or, maybe, are constructor classes the only way to use these types? If that's the case - is that inherent in these types or just the way Haskell does it? Because I was thinking that although you don't know much about these types (e.g., the operations you can perform on k) you should be able to compute height (& size) and leaves :: Tree c k e -> [e] and even replMin on the information that's there in the type. -- Dave -----Original Message----- From: Tom Pledger [mailto:Tom.Pledger@peace.com] Sent: Monday, May 21, 2001 7:25 PM To: haskell(a)haskell.org Subject: Recursive types? David Bakin writes: | I'm having trouble understanding recursive types (e.g., as described in | Functional Programming with Overloading and Higher-Order Polymorphism by | Jones. | | He gives as an example | | | > data Mu f = In (f (Mu f)) | | > data NatF s = Zero | Succ s | > type Nat = Mu NatF | | Among the things I don't get are: | | 1. Comparing this to the non-higher-order type: | | > data NatX = Zero | Succ NatX | | What are the advantages of the higher-order type? What are the | disadvantages (incl. runtime costs)? | | 2. How are values of type Nat represented? (It helps me to think about | these things concretely.) _|_ In _|_ In Zero In (Succ _|_) In (Succ (In _|_)) In (Succ (In Zero)) In (Succ (In (Succ _|_))) In (Succ (In (Succ (In _|_)))) In (Succ (In (Succ (In Zero)))) and so on. If you never care about distinguishing In _|_ from _|_, you can save space and time by declaring `newtype Mu ...' instead of `data Mu ...', in which case Nat's run-time representation is the same size as NatX's. One advantage of such higher-order types is reusability. For example, this type CT c k e = c k (Tree c k e) -- Contained Tree, container, key, element data Tree c k e = Empty | Node (CT c k e) e (CT c k e) can be used with no frills newtype Plain k t = Plain t ... :: Tree Plain () e or with every subtree labelled ... :: Tree (,) String e or with every subtree inside the ST monad import ST ... :: Tree STRef s e etc. I don't know whether this is a shining example of an advantage, and am keen to see other comments. Regards, Tom _______________________________________________ Haskell mailing list Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell

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using haxml dynamically
by Taesch, Luc 22 May '01

22 May '01

How can i use HaXml to produce xml, but in a dynamic way? i mean : 1) what i understand from the example is - u have a type H in haskell - u derive (manally or with drift) an instance Haskell2xml out of it (defines tocontenst, from contents) - u use it, say with to xml, from xml 2) id like to generate an xml structure computed from some schema works, which means that the structure will be build "dynamically" at run time, ie I wont build the structure from an haskell type, not wont i have an haskell2xml instance at hand. (and i dont want to generate an intermediate haskell file and load/compile it) are there a way to create/fill/describe an xml structure "dynamically", ie as a result of some computation (with haxml, i mean) ? a bit like the example 4 from the paper , fixed with the recent names ? This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. CREDIT SUISSE GROUP and each of its subsidiaries each reserve the right to monitor all e-mail communications through its networks. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorised to state them to be the views of any such entity. Unless otherwise stated, any pricing information given in this message is indicative only, is subject to change and does not constitute an offer to deal at any price quoted. Any reference to the terms of executed transactions should be treated as preliminary only and subject to our formal written confirmation.

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Problem to load the file Stack.hs with Hugs98
by Mickaël GAUTIER 21 May '01

21 May '01

Hello, I would like to use the file stack.hs wich is provided with Hugs 98 but the following message errors display: "Haskell98 does not support restricted type synonyms" Can you explain me why and how I can load stack.hs ? Thanks in advance

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