Re: [Haskell-cafe] Scraping boilerplate deriving?

On Tue, Sep 14, 2010 at 01:24:16AM -0700, Kevin Jardine wrote:

I have a set of wrapper newtypes that are always of the same format:

newtype MyType = MyType Obj deriving (A,B,C,D)

where Obj, A, B, C, and D are always the same. Only MyType varies.

A, B, C, and D are automagically derived by GHC using the

{-# LANGUAGE GeneralizedNewtypeDeriving #-}

feature.

I would like to use some macro system (perhaps Template Haskell?) to reduce this to something like

defObj MyType

How about the straightforward?

{-# LANGUAGE CPP #-} #define defObj(t) newtype t = t Obj deriving (A,B,C,D)

defObj(Foo) defObj(Bar) ....

It has the advantage of being (de facto) portable. John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/