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?