#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1-rc2 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): While comment:10 is indeed an odd interaction, these sorts of problems become inevitable. I'm reminded of a scene in the movie Interstellar where a robot describes that his "honesty setting" is at 90%, because that just works out better than being 100% honest. As GHC's type system has become more complicated, users have been requesting it to lower its honesty setting, hiding bits and pieces that look scary. We now have `-fprint- explicit-kinds`, `-fprint-explicit-coercions`, `-fprint-explicit-foralls`, `-fprint-equality-relations`, and `-fprint-explicit-runtime-reps`. Each of these flags are off by default, and each one is essentially an honesty setting. Perhaps with the exception of `-fprint-explicit-coercions`, the fact that GHC lies about these aspects of a program means that programmers may make mistakes -- it's the old "garbage in, garbage out", but in reverse! (with the humans getting and producing the garbage) I don't know how to really solve this, short of #8809, which would lead to Idris-like interactivity in error messages. We could try to figure out when a user has produced garbage in response to a lie that GHC has told and then tell the user to tell GHC not to lie (as we do when we suggest `-fprint-explicit-kinds` in error messages), but I think we'll always be playing catch-up. Instead, we should give the user the direct option (via #8809) to know when GHC is lying and to request the truth. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler