Build issues on GHC 8

[roboguy13]

I think this is related to type checking changes in GHC 8, at least partly. I'm getting a couple errors that look like this:

src/HERMIT/Server/Parser/Crumb.hs:102:7: error:
    • Couldn't match type ‘HERMIT.Server.Parser.Utils.R a0’
                     with ‘Crumb’
      Expected type: ExternalParser Crumb
        Actual type: ExternalParser (HERMIT.Server.Parser.Utils.R a0)
      The type variable ‘a0’ is ambiguous
    • In the expression: external "coForallBody" ForAllCo_Body
[...]

HERMIT.Server.Parser.Utils.R is a type family associated with the External class that is used for parsing (I believe) the JSON values.

I'm also getting some "not in scope" errors, like this:

src/HERMIT/Server/Parser/Crumb.hs:103:9: error:
    • Data constructor not in scope: ForAllCo_Body
    • Perhaps you meant one of these:
        ‘ForAllTy_Body’ (imported from HERMIT.Core),
        ‘ForAllCo_Co’ (imported from HERMIT.Core),
        ‘Forall_Body’ (imported from HERMIT.Core)

I'm not fully sure what change caused this or which constructor should be used in these cases.