#14119: Refactor type patterns -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: 12564, 13910, | 13938, 14038 Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): While investigating #14270 I found that `SpecConstr` was generating rules with massive coercions, like {{{ RULE "SC:foo" f @(a |> <huge coercion expression>) arg1 arg2 = ... }}} Then I mis-read `Note [Matching in the presence of casts]` in `Unify`, and thought that we simply discarded casts. So I had a go at replacing casts in type patterns with a kind of placeholder `UnivCo`. I now think this is probably all wrong, because I still don't understanding of type patterns involving kind casts. But rather than delete my changes entirely I'll attach them here for future reference. The starting point was a new form of `UnivCoProvenance` to use in type patterns; and a `TypePat` type in `Unify. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14119#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler