Bools are not unboxed

[Josef Svenningsson]

Simon Marlow wrote:

>On 06 October 2004 00:53, John Meacham wrote:
>
>  
>
>>This seems like it could be nicely generalized such that all
>>enumeration types unbox to the unboxed integer of their offset. so
>>
>>data Perhaps = Yes | Maybe | No
>>
>>can unbox to an Int# with 0# == Yes 1# == Maybe and 2# == No.
>>    
>>
>
>Yes, a strict enumeration should be implemented as an Int#, both in the
>strictness analyser and also when you {-# UNPACK #-} a constructor
>field.  This is something we'd like to try, but haven't got around to it
>yet.  Maybe a good bite-sized project for a budding GHC hacker? :-)
>
>  
>
Would it really be correct to translate it to Int#? AFAIK, unboxed 
values may not contain bottom while a data type most certainly can. I 
would imagine translating it to Int, and then relying on GHC's optimiser 
to optimize this into Int# whenever possible.

   /Josef