From: simonpj@microsoft.com <unknown>
Date: Sun, 2 Apr 2006 21:59:11 +0000 (+0000)
Subject: Improve newtype deriving
X-Git-Tag: Before_FC_branch_merge~556
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=aa2c486e51caa0386aaff0d1b866a60316500b41;hp=aa2c486e51caa0386aaff0d1b866a60316500b41;p=ghc-hetmet.git

Improve newtype deriving

Ross Paterson pointed out a useful generalisation of GHC's
newtype-deriving mechanism.  This implements it.  The idea
is to allow
	newtype Wrap m a = Wrap (m a) deriving (Monad, Eq)
where the representation type doesn't start with a type
constructor.

Actually GHC already *did* implement this, but the eta-ok
check in TcDeriv missed a case, so there was a lurking bug.

This patches fixes the documentation too.  drvrun019 tests.
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