#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):
I've run into this while trying to hack together something like http://gcc.godbolt.org/, but for Haskell,
`pretty` appears to be the same library GHC uses and as pointed out by bgamari already supports annotations. Does anyone know if they diverged in functionality/semantics? If not, would it be a useful step to migrate GHC's `Doc` to annotated version? There were a few deviations, although I think most of them have been
Ahh, interesting. patched up by thomie (see #10735).
I think an argument against it is that it doesn't have a `Monad` instance, but I don't immediately see the benefit of having it.
I think you ultimately **need** a `Monad` instance since this allows you to project your annotations back to the output currently producted by GHC. AFAICT the Hughes pretty-printer doesn't admit an efficient, correct monadic bind. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8809#comment:21 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler