#8826: Allow more coercions in Safe Haskell -------------------------------------+------------------------------------ Reporter: goldfire | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by simonpj):
Why do we need this? In order to forestall any possible abstraction breaking.
I don't buy this. Why are inferred '''roles''' different from inferred '''kinds'''? What bad things would happen if we simply abandoned the restriction that the constructors of the type must be in scope to do allow coercion from `(T Int)` to `(T Age)`? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8826#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler