It may not be a bug, because you do get an error, but it's certainly an
infelicity because the error comes out much too late. I'll Trac this and fix
in due course. Thanks for raising it.
Simon
| -Original Message-
| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of
Dougal Stanton, Thu, 9 Aug 2007 16:57:26 +0100:
Is there a reason why automatic derivation of Ord without Eq doesn't
do the sensible thing and just derive Eq anyway?
newtype Id a = Id { a :: String }
deriving (Read, Show, Eq, Ord)
newtype Ego a = Ego { b :: String }
I would say that qualifies as a bug because it relays an error from compile
time to run time.
Andreas
- Original Message -
From: Dougal Stanton [EMAIL PROTECTED]
To: haskell-cafe haskell-cafe@haskell.org
Sent: Thursday, August 09, 2007 5:57 PM
Subject: [Haskell-cafe] Derivation of Eq
I wrote:
instance Eq Ego = Eq Ord where ...
This should have been
instance Eq (Ego a) = Ord (Ego a)
Malte
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Andreas Marth wrote:
I would say that qualifies as a bug because it relays an error from compile
time to run time.
It doesn't relay anything to run time - ghci has to _compile_ the
expressions you give it too. If you _compile something_ successfully,
you will know that _it_ will not fail in
