Due to a large amount of spam we do not allow new users to create repositories, they are "external" users. If you are a new user and want to create a repository, for example for forking GHC, open a new issue on ghc/ghc using the "get-verified" issue template
**Update** (March, 2014): There is a draft paper describing roles, including much discussion of design decisions, [ here](http://www.cis.upenn.edu/~eir/papers/2014/coercible/coercible-ext.pdf).
The idea of *roles* comes from the paper [ Generative Type Abstraction and Type-level Computation](http://www.seas.upenn.edu/~sweirich/papers/popl163af-weirich.pdf), published at POPL 2011. The implementation of roles in GHC, however, is somewhat different than stated in that paper. This page focuses on the user-visible features of roles.
The idea of *roles* comes from the paper [ Generative Type Abstraction and Type-level Computation](http://www.seas.upenn.edu/~sweirich/papers/popl163af-weirich.pdf), published at POPL 2011. The implementation of roles in GHC, however, is somewhat different than stated in that paper. This page focuses on the user-visible features of roles. [RolesImplementation](roles-implementation) talks about the implementation in GHC. See also [ Richard's blog post about roles](http://typesandkinds.wordpress.com/2013/08/15/roles-a-new-feature-of-ghc/). (Note: some aspects of that blog post are out of date, as of December 17, 2013.)
See also
See also this email thread: [ More GND + role inference woes](http://www.haskell.org/pipermail/ghc-devs/2013-October/003003.html).
- Our ICFP 2014 paper [ Safe Coercions](http://www.cis.upenn.edu/~eir/papers/2014/coercible/coercible-ext.pdf), which gives lots of motivation and details, including the `Coercible` class.
-[Roles2](roles2) which identifies a difficulty with the design in the paper, and some possibilities for solving it.
-[RolesImplementation](roles-implementation) talks about the implementation in GHC.
-[ Richard's blog post about roles](http://typesandkinds.wordpress.com/2013/08/15/roles-a-new-feature-of-ghc/). (Note: some aspects of that blog post are out of date, as of December 17, 2013.)
- This email thread: [ More GND + role inference woes](http://www.haskell.org/pipermail/ghc-devs/2013-October/003003.html).
