Unlifted data types

[Edward Z. Yang]

Hello friends,

After many discussions and beers at ICFP, I've written up my current
best understanding of the unlifted data types proposal:

    https://ghc.haskell.org/trac/ghc/wiki/UnliftedDataTypes

Many thanks to Richard, Iavor, Ryan, Simon, Duncan, George, Paul,
Edward Kmett, and any others who I may have forgotten for crystallizing
this proposal.

Cheers,
Edward