id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
1311,newtypes of unboxed types disallowed - documentation bug and/or feature request,Isaac Dupree,,"Tested in 6.6.1 and today's 6.7 (which claims to be version 6.7.20070418),

{{{newtype FastBool = FastBool Int#}}}

doesn't work. However this is not documented in the unboxed-types documentation in the User's Guide that lists similar restrictions http://www.haskell.org/ghc/docs/latest/html/users_guide/primitives.html

Similarly (maybe), in phantom type arguments, even in GADTs where kind inference could be at work

{{{data Boo a where Boo :: Int# -> Boo Int#}}}

doesn't work.

I tried {{{newtype ( FastBool :: # ) = ...}}} , and {{{data Boo ( a :: # ) where...}}} , which just confused GHC.

Is there a reason that coercions of unlifted types shouldn't work, or is it just unimplemented?  (inspired by looking at GHC's 
compiler/utils/FastTypes.lhs and thinking that using newtypes instead of type synonyms in places like that would improve type-safety)",feature request,new,low,_|_,Compiler,6.6.1,,,,Unknown/Multiple,Unknown/Multiple,,Unknown,,,,