Personally I would like {-# OPTIONS -fglasgow-exts -fgenerics -} module Blog.Types where family Usual = (Eq, Ord, Read, Show, Typeable) data BlogEntry = Entry EpochSeconds Name Email Title Body deriving Usual newtype Name = Name String deriving Usual newtype Title = Title String deriving Usual newtype Body = Body String deriving Usual Of course, if you're doing that, you might as well change those last 3 lines with newtype-schema NamedString = NamedString String deriving Usual instantiate NamedString with Name, Title, Body To me, that is very clear. Syntax-wise, I am sure things can be improved (but I rather like 'family', 'foo-schema' and 'instantiate', but not really the 'with'). Jacques Alex Jacobson wrote:

Consider this module for a blog entry that I will want to put in various generic collections that require Ord

{-# OPTIONS -fglasgow-exts #-} module Blog.Types where import Data.Typeable import Data.Generics

data BlogEntry = Entry EpochSeconds Name Email Title Body deriving (Eq,Ord,Read,Show,Typeable)

newtype Name = Name String deriving (Eq,Ord,Read,Show,Typeable) newtype Title = Title String deriving (Eq,Ord,Read,Show,Typeable) newtype Body = Body String deriving (Eq,Ord,Read,Show,Typeable)

It seems really unnecessarily verbose. Having to add the OPTION header AND import Data.Typeable and Data.Generics just to derive Typeable is a beat-down. It is even more of a beat-down to have to add a deriving clause for every newtype to make this all work nicely. Is there a way to make all types automatically derive everything unless there is an explicit instance declaration otherwise?

{-# OPTIONS -fglasgow-exts -fgenerics -fderiving#-} module Blog.Types where

data BlogEntry = Entry EpochSeconds Name Email Title Body newtype Name = Name String newtype Title = Title String newtype Body = Body String Isn't that much nicer?

-Alex-

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