Expose initSessionWithMessage

[Avi-D-coder]

Needed by haskell/haskell-ide-engine#1589

Github and vim automatically added the newline so I gave up.

[fendor]

Thanks!

[fendor]

Actually, now I am not entirely sold on the idea of just exposing initSessionWithMessage. Maybe we could change the type of initializeFlagsWithCradleWithMessage to also return the ComponentOptions if there are any? Otherwise the function initializeFlagsWithCradleWithMessage is rather useless, esepcially for Haskell IDE Engine, and I think we are the only users of that function.

Would you mind brainstorming a better API for initializeFlagsWithCradleWithMessage?

What do you think about:

initializeFlagsWithCradleWithMessage ::
  GhcMonad m
  => Maybe G.Messager
  -> FilePath -- ^ The file we are loading the 'Cradle' because of
  -> Cradle   -- ^ The cradle we want to load
  -> m (CradleLoadResult (ComponentOptions, m G.SuccessFlag)) -- ^ Whether we actually loaded the cradle or not.

Disadvantage: looks dirty
Advantage: Does not force users of the lib to re-implement initializeFlagsWithCradleWithMessage with the newly exposed initSessionWithMessage.

[Avi-D-coder]

@fendor If we are truly the only user of this function we can change the return type and willing to make a breaking change, this would also get ride of the unreachable case (haskell/haskell-ide-engine#1589 (comment)). I was working under the erroneous assumption that a breaking change was not an option.

Ghcide does not use initializeFlagsWithCradleWithMessage, are there any other known users of hie-bios?

[fendor]

Ghcide uses nothing of the HIE.Bios.Ghc namespace and I am not aware of other big users. Moreover, next release will have breaking changes regarding the Cradle type anyways

[ndmitchell]

Breaking changes are not a big deal to ghcide - we expect them at this stage in the maturity cycle.