[Haskell] "Classic" vs. "Cunning Newtype" Derivation

John Meacham john at repetae.net
Mon Mar 7 19:20:14 EST 2005

On Mon, Mar 07, 2005 at 04:06:44PM -0800, Ashley Yakeley wrote:
> I make quite a lot of use of "cunning newtype" deriviation (in GHC), 
> because it's easy to understand.
>   newtype Mytype = MkMytype T deriving C
> However, if I use one of the standard derivable classes (Eq, Ord, Enum, 
> Bounded, Show, and Read), I believe that form of deriving takes priority.
> AFAICT from the H98 Report ch. 10, for Eq, Ord and Bounded this works 
> out as the same thing, Enum doesn't apply, and Read and Show do 
> something different. Is this correct, or are there subtle differences?

Read, Show, Typeable, and Data are the only differences AFAIK.

John Meacham - ⑆repetae.net⑆john⑈ 

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