#8782: Using GADT's to maintain invariant in GHC libraries ------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: task | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- I rewrote `compiler/utils/OrdList.lhs` using a GADT to preserve some invariants stated only in comments — an excellent chance for `ghc` to eat its own proverbial dog food I feel :) The type signatures remain the same so it should be a drop-in replacement but it does use some GHC features that are too recent (closed type families in particular, the `IsList` instance can be removed) making it ineligible for inclusion I believe. hvr on `#ghc` suggested that I submit a patch anyway and that it could be implemented at a later date (they said `ghc` must be able to be compiled by the last two previous major versions), if this is useful then I will translate `Bag.hls` which has the same invariants but more complicated functions. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8782 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler