- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] HDBC 2.1, UTF8 and Umlauts
by John Goerzen 04 May '09

04 May '09

Günther Schmidt wrote: > Hi John, > > I'm afraid so. > > If it came back as an SqlString "G\252nni" then it propably wouldn't > be a problem. Can you boil this down to a few-line self-contained test program so I can try it myself? I do have test cases for Unicode stuff and they are all passing here. I would like to be able to eliminate your environment as a culprit. Incidentally, could you run make test in the HDBC-sqlite3 source directory? > > > > > Am 04.05.2009 um 20:47 schrieb John Goerzen: > >> Günther Schmidt wrote: >>> Hi John, >>> >>> what I just noticed is that *all* strings come back as >>> SqlByteStrings. >> That's normal, and pretty much irrelevant, since fromSql takes care >> of it. >> >> It's documented, even: the SqlByteString is assumed to be in UTF-8, >> and >> is decoded when converted to a String. >> >> It is not correct to have \252 in the SqlByteString. The proper >> sequence there is \xc3\xbc. When converted to String, *then* it >> should >> be \252. >> >> Are you positive you're seeing \252 in the SqlByteString? That >> doesn't >> make any sense to me. It's not a valid UTF-8 encoding. >> > > How have Umlauts been behaving on your end? Were they as mean to you > as they were to me? > > > >>> ie. I get my "Günni", (G\252nni), back as an SqlByteString "G\252nni" >>> instead of an SqlString "G\252nni". >>> >>> So when I cast, ie. fromSql x :: String, I get an "G\65533nni", which >>> is where the garbling occurs. >>> >>> >>> BTW this is the 3rd time now that I'm writing the same bloody email, >>> my email client "clipped" the previous 2. >>> >>> Günther >>> >>> > >

1 0

Re: [Haskell-cafe] HDBC 2.1, UTF8 and Umlauts
by John Goerzen 04 May '09

04 May '09

Günther Schmidt wrote: > Hi John, > > what I just noticed is that *all* strings come back as SqlByteStrings. That's normal, and pretty much irrelevant, since fromSql takes care of it. It's documented, even: the SqlByteString is assumed to be in UTF-8, and is decoded when converted to a String. It is not correct to have \252 in the SqlByteString. The proper sequence there is \xc3\xbc. When converted to String, *then* it should be \252. Are you positive you're seeing \252 in the SqlByteString? That doesn't make any sense to me. It's not a valid UTF-8 encoding. > > ie. I get my "Günni", (G\252nni), back as an SqlByteString "G\252nni" > instead of an SqlString "G\252nni". > > So when I cast, ie. fromSql x :: String, I get an "G\65533nni", which > is where the garbling occurs. > > > BTW this is the 3rd time now that I'm writing the same bloody email, > my email client "clipped" the previous 2. > > Günther > >

1 0

When is it OK to create a new mailing list?
by Mads Lindstrøm 04 May '09

04 May '09

Hi I wanted a mailing list for my project WxGeneric and I am wondering when it is OK to do so? How big must the potential audience be? Is there any kind of etiquette or guidelines? Here http://haskell.org/mailman/admin it says that I must have "the proper authority" to create a mailing list. What is meant by "proper authority"? Can I just try to create one and see if I am successful? Or must I request someone to do it? Regards, Mads Lindstrøm

6 5

HDBC 2.1, UTF8 and Umlauts
by Günther Schmidt 04 May '09

04 May '09

Hi guys, for some reason, any way I try, all the Umlauts get garbled with HDBC 2.1. HDBC 1.16 worked fine with any backend (ODBC, Sqlite3, ... what have you). Anybody else had similar problems and knows how to solve this? Günther

2 1

Estimating the time to garbage collect
by Neil Davies 04 May '09

04 May '09

Hi With the discussion on threads and priority, and given that (in Stats.c) there are lots of useful pieces of information that the run time system is collecting, some of which is already visible (like the total amount of memory mutated) and it is easy to make other measures available - it has raised this question in my mind: Given that you have access to that information (the stuff that comes out at the end of a run if you use +RTS -S) is it possible to estimate the time a GC will take before asking for one? Ignoring, at least for the moment, all the issues of paging, processor cache occupancy etc, what are the complexity drivers for the time to GC? I realise that it is going to depend on things like, volume of data mutated, count of objects mutated, what fraction of them are live etc - and even if it turns out that these things are very program specific then I have a follow-on question - what properties do you need from your program to be able to construct a viable estimate of GC time from a past history of such garbage collections? Why am I interested? There are all manners of 'real time' in systems, there is a vast class where a statistical bound (ie some sort of 'time to complete' CDF) is more than adequate for production use. If this is possible then it opens up areas where all the lovely properties of haskell can be exploited if only you had confidence in the timing behaviour. Cheers Neil

4 6

gcd
by Steve 04 May '09

04 May '09

[Question moved over from Haskell-Beginners] I had a look at the gcd definition in GHC 6.10.1 ghc-6.10.1/libraries/base/GHC/Real.lhs -- | @'gcd' x y@ is the greatest (positive) integer that divides both @x@ -- and @y@; for example @'gcd' (-3) 6@ = @3@, @'gcd' (-3) (-6)@ = @3@, -- @'gcd' 0 4@ = @4@. @'gcd' 0 0@ raises a runtime error. gcd :: (Integral a) => a -> a -> a gcd 0 0 = error "Prelude.gcd: gcd 0 0 is undefined" gcd x y = gcd' (abs x) (abs y) where gcd' a 0 = a gcd' a b = gcd' b (a `rem` b) Why is gcd 0 0 undefined? http://en.wikipedia.org/wiki/Greatest_common_divisor says: "It is useful to define gcd(0, 0) = 0 and lcm(0, 0) = 0 because then the natural numbers become a complete distributive lattice with gcd as meet and lcm as join operation. This extension of the definition is also compatible with the generalization for commutative rings given below." An added advantage, for haskell, of defining gcd 0 0 = 0 is that gcd would change from being a partial function to a total function. Regards, Steve

8 11

Research in functional programming
by Louis Wasserman 04 May '09

04 May '09

Where might I find or submit a paper on functional data structures? Examples I've found so far include ICFP <http://www.icfpconference.org/> and the JFP <http://journals.cambridge.org/action/displayJournal?jid=JFP>, but Google hasn't found me anything else. Louis Wasserman wasserman.louis(a)gmail.com

4 4

*system*-time timeout?
by brian＠lorf.org 04 May '09

04 May '09

System.Timeout.timeout is OK for wall clock time, but can I limit the amount of system time an IO action can take?

1 0

converting IOException to Either in ErrorT
by brian＠lorf.org 04 May '09

04 May '09

I wrote this to make it a little nicer to catch IO exceptions and convert them to ErrorT failure: onExceptionThrowError :: (Error ce) => IO a -> (String -> ce) -> ErrorT ce IO a onExceptionThrowError a ce = liftIO (try a) >>= either (\(e :: IOException) -> throwError (ce (show e))) return So now I can do, e.g., writeFile fp s `onExceptionThrowError` SpecificErrorConstructor ... It works, but seems bad. Please let me know if you see ways to improve it. Thanks.

2 1

ANN: Silkworm game
by Duane Johnson 03 May '09

03 May '09

Reprinted from my blog post [1]: === The semester is over, my final project was a success (at least in that I passed the class) and it’s time now to release the game I made for Graphics 455: Silkworm! This is my first full application in Haskell. The process has been an enlarging experience–I’ve come to really enjoy the mental work that goes into thinking about a program in a functional way. I highly recommend the challenge to other software engineers. Silkworm combines the Hipmunk binding to Chipmunk 2D Game Dynamics with OpenGL, and GLFW (an alternative to GLUT). It’s built to work on Mac OS X, but it uses cross-platform libraries so it should be fairly easy to port to other platforms. The source code is here [2] and below are some screenshots [1] -- Duane Johnson (canadaduane) === [1] http://blog.inquirylabs.com/2009/05/02/silkworm-game-written-in-haskell/ [2] http://inquirylabs.com/downloads/Silkworm.tgz

6 11