#15192: Refactor of Coercion -------------------------------------+------------------------------------- Reporter: ningning | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4747 Wiki Page: | -------------------------------------+------------------------------------- Changes (by goldfire): * cc: sweirich@… (added) Comment: I agree with comment:5. Note that the new form is essentially a generalized form of `Refl`, which also has an unrestricted role parameter. One area where the new coercion form is simpler is when we need `t ~r (t |> g)`. Currently, this is `Sym (Coherence (Refl r t) g)`. The new form would be `EraseEqCo r t (CastTy t g) g`. I do suppose that, as sharing is destroyed, the new form could be worse than the original one. The truth is that Stephanie and I have been using this new form in our work for quite some time now, and this feels like just bringing GHC up to speed. But perhaps the old form is more convenient for implementation. I'd love to bring Stephanie in on the conversation. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15192#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler