Promotion of newtypes

[dreixel]

{-# LANGUAGE DataKinds          #-}
{-# LANGUAGE KindSignatures     #-}
{-# LANGUAGE GADTs              #-}

newtype A = A Int
data B (x :: A)

The program above raises the error: A of kind * is not promotable. The program compiles fine if we declare A using data instead of newtype. Is there a good reason to prevent promotion of newtypes?

[simonpj]

Right, I've fixed this.

Simon

[simonpj@…]

commit b8739b28f5bc855b7c5406425b516698cf3b2f0d

Author: Simon Peyton Jones <simonpj@microsoft.com>
Date:   Fri Dec 21 08:05:58 2012 +0000

    Allow newtypes to be promoted
    
    Fixes Trac #7488

 compiler/basicTypes/DataCon.lhs |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)