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(Pre-) Announce: Data.GDS 0.1.0
by Uwe Hollerbach 01 Jun '09

01 Jun '09

Hello, all, I'm hereby announcing Data.GDS, a small module to write and (eventually -- that's part of the "pre") read GDS files. For those of you not in the semiconductor biz, GDS-II is one of the classic formats of the industry. It's perhaps ever so slightly obsolete at this point, as the OASIS format is in the process of displacing it, but there are still huge numbers of designs in GDS format, and lots and lots of tools deal with it. Since I'm a sad sick weirdo(*), I spent a perfectly nice & sunny NorCal day hacking up this initial version of this module. It is to the point where it can generate a GDS file of your devising, although your specification of it still has to be at a very low level. It would be, and eventually will be, nicer to specify things at a higher level of abstraction. Also, it will eventually be nice to be able to read GDS files, returning an array of GDSRecord. I know how to do that, and I plan to, but I haven't got there yet. This ought to already be properly cabalized, and there's a small test program included; run it, save the output somewhere, and compare that with the sample GDS file which I also included in the tarball. If you examine the GDS file itself, you will see that, although it is small, it does in fact contain vital bits of design which will no doubt enable the biz to continue Moore's law for at least another century or so. Once I've implemented the reader, I'll upload this to hackage; in the meantime, if any of you are especially interested in what the rest of the interface to this should look like, I'm happy to hear your suggestions! Uwe (*) In point of fact, I am neither sad nor sick; I am in fact mostly happy & healthy. The reason I wasn't out taking a long walk today was because, alas, I dinged one achilles tendon a few days ago, and wanted to let it heal a bit... as to the "weirdo" charge, I beg you, gentle readers, avert your eyes while I plead no contest! :-)

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Re: [Haskell-cafe] Parsec float
by Bartosz Wójcik 31 May '09

31 May '09

On Friday 29 May 2009 08:34:36 you wrote: > myfloat = try (do{ symbol "-"; n <- float; return (negate n) }) <|> > try float <|> > do { i<-integer; return(fromIntegral i) } Thank you, this is an easy and nice solution. I've made it a bit prettier optically: myFloat = try (symbol "-" >> float >>= return . negate) <|> try float <|> (integer >>= return . fromIntegral) Best regards, Bartek

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Lazy Parsing
by Günther Schmidt 31 May '09

31 May '09

Hi all, is it possible to do lazy parsing with Parsec? I understand that one can do that with polyparse, don't know about uulib, but I happen to be already somewhat familiar with Parsec, so before I do switch to polyparse I rather make sure I actually have to. The files it has to parse is anywhere from 500 MB to 5 GB. Günther

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Re: Lazy Parsing
by Guenther Schmidt 31 May '09

31 May '09

Dear Doaitse, thank you very much for your help. > > I am curious to know what made you go wrong with the tutorial, and > caused that you could not find the solution below? > Well let's first agree that I'm not very bright. I hate to admit it, but it's a simple fact ;-). Second let's agree that the uu-parsinglib is a *very* sophisticated beast, I have not seen anything else like it out there, my sincere congratulations for it. Thirdly the tutorial is also a very sophisticated beast, and forthly, well just see point 1 :-). And I just figured out why I was unable to write even that simple parser. The code you sent me works just fine, I copied and pasted it, no problems. But, as soon as I comment out the "main" function the type checker complains, because now the ghci's type checker can no longer infer the types of pDate or pDot. And this is exactly what happened. I kept getting error messages from ghci, eventhough I had defined my parsers possible correctly, but, *minus* the type signatures *and* minus any main function that called it. In hindsight I realize that this is a trap I have walked into many times before, I guess I still have not acquired a Haskellers intuition. I promise to do better next time :) Günther

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Type families in export lists
by Maurício 31 May '09

31 May '09

Hi, How do I include type families (used as associated types) in a module export list? E.g.: class MyClass a where type T a :: * coolFunction :: Ta -> a (...) If I just include MyClass and its functions in the list, instances in other modules complain they don't know T, but I wasn't able to find how (where) to include T in the list. Thanks, Maurício

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(no subject)
by Vladimir Reshetnikov 31 May '09

31 May '09

Hi, Seems that Haskell allows to specify "dummy" type variables in a declaration of a type synonym, which do not appear in its right-hand side. This can lead to interesting effects, which appears differently in GHC and Hugs. I would like to know, what behavior is correct according to the haskell 98 report. 1) ------------------------------------------ type F a = Int class A a where foo :: A b => a (F b) ------------------------------------------ GHC - OK Hugs - Illegal type "F b" in constructor application 2) ------------------------------------------ type F a = Int class A a where foo :: F a instance A Bool where foo = 1 instance A Char where foo = 2 xs = [foo :: F Bool, foo :: F Char] ------------------------------------------ GHC: M.hs:14:6: Ambiguous type variable `a' in the constraint: `A a' arising from a use of `foo' at M.hs:14:6-8 Probable fix: add a type signature that fixes these type variable(s) M.hs:14:21: Ambiguous type variable `a1' in the constraint: `A a1' arising from a use of `foo' at M.hs:14:21-23 Probable fix: add a type signature that fixes these type variable(s) Hugs: [1,2] Thanks, Vladimir

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GHCi vs. Hugs (record syntax)
by Vladimir Reshetnikov 31 May '09

31 May '09

Hi, I tried to evaluate this expression: head[[]{}] GHCi: [] Hugs: ERROR - Empty field list in update What is the correct behavior? Thanks, Vladimir

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Which type variables are allowed in a context?
by Vladimir Reshetnikov 31 May '09

31 May '09

Hi, Consider this (a bit pathological) Haskell code: -------------------------------------- class A a where foo :: A (b d) => a (c b) -------------------------------------- GHC compiles it successfully, but Hugs rejects it: Ambiguous type signature in class declaration *** ambiguous type : (A a, A (b c)) => a (d b) *** assigned to : foo What is the correct behavior, and which part of the haskell 98 report explains this? Thanks, Vladimir

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Question on kind inference
by Vladimir Reshetnikov 31 May '09

31 May '09

Hi, Consider this Haskell code: ----------------------------------------------- class A a where foo :: a b class B a class (A a, B a) => C a ----------------------------------------------- GHC compiles it without errors, but Hugs rejects it: "Illegal type in class constraint". What is the correct behavior, and which part of the haskell 98 report explains this? Thanks, Vladimir

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Re: [Haskell-cafe] Parsing command lines
by Kalman Noel 31 May '09

31 May '09

Patai Gergely schrieb: > is there a function that can safely split a command line into a FilePath > to the executable and its parameters? In the yi source code, in HConf.Utils, there's a function that does part of what you want, but maybe incorrectly (because I wrote it, and it traverses the string in a rather primtive way). -- | Break up a string the way a shell breaks up a command into arguments. -- Similar to 'words', but respects quotes and escaped spaces. TODO: Verify -- this function. shellWords :: String -> [String]

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