#10494: Representational equalities over AppTys are not hard failures -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: merge Priority: normal | Milestone: 7.10.3 Component: Compiler | Version: Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T10494 Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by crockeea): I'm about to release a package that triggers the bug, so it currently has crufty work-around code that I'd like to kill. I have a collection of functions that coerce functions of one signature to functions of another signature. Many of the definitions are simply `coerce`, but the explicit functions are needed for type inference. Here's an example: Instead of writing {{{ coerceBasis :: (Coercible (o r) (n m' r)) => Tagged '(m,m') ([o r]) -> Tagged m [n m' r] coerceBasis = coerce }}} I have to write {{{ coerceBasis :: (a ~ (o r), b ~ (n m' r), Coercible a b) => Tagged '(m,m') ([o r]) -> Tagged m [n m' r] coerceBasis = coerce }}} introducing two new intermediate type variables and constraints. Is this enough of a problem to make you go through the work of releasing 7.10.3 just for it? Certainly not. Mostly I was just unsure of the status of the patch and didn't want the original bug to be forgotten. That said, I *would* like it resolved sooner rather than later. I saw something on GHC-Devs about releasing builds, which makes a lot of sense to me. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10494#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler