fwiw, this s what I'm doing till I figure out a better way:
import System.Time
data MyTime = MyTime Integer Integer
deriving (Typeable,Data)
myTimeToClockTime (MyTime a b) = TOD a b
myTimeFromClockTime (TOD a b) = MyTime a b
and use MyTime in the happstack state.
2009/10/5 Thomas Hartman
I want to patch the time package, which I darcs got head on. Goal is to be able to do newtype deriving for UTCTime which I reckon is the base time value, for use in happstack applications state.
basically, need instances for UTCTime, for Data and Typeable.
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<patch-tag> I just darcs got time package and attempted to install. cabal install didn't work because missing configure fle. there's a .ac file there, so I tried first autoconf, then cabal install. configure file got created, but failed with config.status: error: cannot find input file: include/HsTimeConfig.h.in. now what? <patch-tag> my goal is to patch time package so can do data generics deriving.
<Berengal> patch-tag, use System.Time instead? * Berengal shrugs and sighs [12:20] <patch-tag> could try that... *** o-regalia (n=o-regali@host-0-130.mimpvbg.clients.pavlovmedia.com) has quit: "Lost terminal" <Berengal> It already has a Serializeable instance defined in one of the happstack modules, so there's probably a Typeable and Data instance somewhere as well
<Berengal> patch-tag, unfortunately, UTCTime has a component of a hidden datatype which isn't an instance of Typeable or Data, and since it's not exported it's impossible to create the instance as well <Berengal> If it were exported, it'd be pretty easy <patch-tag> hw can I use UTCTime, deriving Typeable and Data? (want to use UTCTime in happstack). <patch-tag> http://moonpatio.com/fastcgi/hpaste.fcgi/view?id=4278#a4278 <patch-tag> I guess I should have said I'd like to use newtype deriving rather than define instance myself if that's possible.
<Berengal> patch-tag, that's possible, but could break other things. The correct solution is to patch the existing package, but that takes time <Berengal> patch-tag, Day, or something. Can't remember off the top of my head *** paolino (n=paolino@87.7.161.162) has quit: "Leaving." <ski> Philonous : if you can't implement both operations (satisfying laws), though, it is probably better to make a new class [12:09] <patch-tag> Berengal: a package is hidden if when you do :info in ghci, it comes out as fully qualified, right? <patch-tag> pity also that newtype deriving doesn't give you a nicer error message like "deriving choked at type blah" <Berengal> patch-tag, it comes fully qualified if it's not imported, so you'll have to try to import it to see if it's really hidden [12:10]
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Seems like the right thing to do is patch the time package anyway.
File Edit Options Buffers Tools Haskell Help {-# LANGUAGE DeriveDataTypeable #-} module TypeableTime where
import Data.Time import Data.Data import Data.Generics import Data.Typeable
-- doesn't work --data MyUTCTime = MyUTCTime UTCTime -- deriving (Typeable,Data)
-- should I work up to UTCTime by doing this...? data MyDay = MyDay {toMyDayModifiedJulianDay :: Integer} deriving (Typeable,Data)
newtype MyString = MyString String deriving (Read,Show,Ord,Eq,Typeable,Data)
-- should I just modify time package? is this easier?