I'm not sure I understand how this solves my problem. Its possible that
I can use Derive not to need all the newtype declarations at all, but,
if I do need them, I'm not sure how Derive reduces the overall amount of
boilerplate here.
Perhaps I should define a TH function that takes
$(newtype' Name String)
And converts it to a
newtype Name = Name String deriving (Eq,Ord,Read,Show,Typeable)
-Alex-
Neil Mitchell wrote:
Hi
{-# 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)
First off, never use OPTIONS, use OPTIONS_GHC instead. OPTIONS is the
old way of doing it.
Secondly, if you add {-# OPTIONS_DERIVE
--derive=Eq,Ord,Read,Show,Typeable #-} then running your code through
with Derive should give you the magic that you require. Plus it will
also work on Hugs, and not require your OPTIONS_GHC anyway.
Derive: http://www-users.cs.york.ac.uk/~ndm/derive/
Thanks
Neil
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