#8809: Prettier error messages? -------------------------------------+------------------------------------- Reporter: joelteon | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): #8809,#10073,#10179 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): For the record, some time ago I actually tried quickly prototyping the ideas laid out in comment:3. The branch can be found [[https://github.com/ghc/ghc/compare/master...bgamari:error|here]]. The only slightly annoying issue with the approach is that it requires adding an index to all mentions of `Doc`, leading to a rather difficult to rebase branch. That being said, I really don't think there's a whole lot of work here if we agree that this is the right approach. If someone was motivated, I'm rather confident that we could get the painful refactoring changes into the tree within the space of a weekend. Of course, the dynamically-typed alternative proposed by Richard in comment:9 is also still on the table. However, I suspect we'd rather want `Doc` to look like, {{{#!hs data Doc = forall a. (Typeable a, Outputable a) => Embed a | Empty | ... }}} to ensure that the consumer can always, at very least, output a human readable representation of the payload. It's not clear which of these options is preferrable; I'll admit that the dynamically-typed option feels a bit like we are trading precision and long-term maintainability for some temporary convenience, but perhaps this is too pessimistic a view. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8809#comment:31 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler