Add kind equalities to GHC.

This implements the ideas originally put forward in
"System FC with Explicit Kind Equality" (ICFP'13).

There are several noteworthy changes with this patch:
 * We now have casts in types. These change the kind
   of a type. See new constructor `CastTy`.

 * All types and all constructors can be promoted.
   This includes GADT constructors. GADT pattern matches
   take place in type family equations. In Core,
   types can now be applied to coercions via the
   `CoercionTy` constructor.

 * Coercions can now be heterogeneous, relating types
   of different kinds. A coercion proving `t1 :: k1 ~ t2 :: k2`
   proves both that `t1` and `t2` are the same and also that
   `k1` and `k2` are the same.

 * The `Coercion` type has been significantly enhanced.
   The documentation in `docs/core-spec/core-spec.pdf` reflects
   the new reality.

 * The type of `*` is now `*`. No more `BOX`.

 * Users can write explicit kind variables in their code,
   anywhere they can write type variables. For backward compatibility,
   automatic inference of kind-variable binding is still permitted.

 * The new extension `TypeInType` turns on the new user-facing
   features.

 * Type families and synonyms are now promoted to kinds. This causes
   trouble with parsing `*`, leading to the somewhat awkward new
   `HsAppsTy` constructor for `HsType`. This is dispatched with in
   the renamer, where the kind `*` can be told apart from a
   type-level multiplication operator. Without `-XTypeInType` the
   old behavior persists. With `-XTypeInType`, you need to import
   `Data.Kind` to get `*`, also known as `Type`.

 * The kind-checking algorithms in TcHsType have been significantly
   rewritten to allow for enhanced kinds.

 * The new features are still quite experimental and may be in flux.

 * TODO: Several open tickets: #11195, #11196, #11197, #11198, #11203.

 * TODO: Update user manual.

Tickets addressed: #9017, #9173, #7961, #10524, #8566, #11142.
Updates Haddock submodule.

1 files changed, 5 insertions, 5 deletions

diff --git a/compiler/ghci/Debugger.hs b/compiler/ghci/Debugger.hs
index ccd7f16e0e..2b9e732c4b 100644
--- a/compiler/ghci/Debugger.hs
+++ b/compiler/ghci/Debugger.hs
@@ -53,7 +53,7 @@ pprintClosureCommand bindThings force str = do
   let ids = [id | AnId id <- tythings]
 
   -- Obtain the terms and the recovered type information
-  (subst, terms) <- mapAccumLM go emptyTvSubst ids
+  (subst, terms) <- mapAccumLM go emptyTCvSubst ids
 
   -- Apply the substitutions obtained after recovering the types
   modifySession $ \hsc_env ->
@@ -69,7 +69,7 @@ pprintClosureCommand bindThings force str = do
                     docterms)
  where
    -- Do the obtainTerm--bindSuspensions-computeSubstitution dance
-   go :: GhcMonad m => TvSubst -> Id -> m (TvSubst, Term)
+   go :: GhcMonad m => TCvSubst -> Id -> m (TCvSubst, Term)
    go subst id = do
        let id' = id `setIdType` substTy subst (idType id)
        term_    <- GHC.obtainTermFromId maxBound force id'
@@ -88,13 +88,13 @@ pprintClosureCommand bindThings force str = do
          Just subst' -> do { traceOptIf Opt_D_dump_rtti
                                (fsep $ [text "RTTI Improvement for", ppr id,
                                 text "is the substitution:" , ppr subst'])
-                           ; return (subst `unionTvSubst` subst', term')}
+                           ; return (subst `unionTCvSubst` subst', term')}
 
    tidyTermTyVars :: GhcMonad m => Term -> m Term
    tidyTermTyVars t =
      withSession $ \hsc_env -> do
-     let env_tvs      = tyThingsTyVars $ ic_tythings $ hsc_IC hsc_env
-         my_tvs       = termTyVars t
+     let env_tvs      = tyThingsTyCoVars $ ic_tythings $ hsc_IC hsc_env
+         my_tvs       = termTyCoVars t
          tvs          = env_tvs `minusVarSet` my_tvs
          tyvarOccName = nameOccName . tyVarName
          tidyEnv      = (initTidyOccEnv (map tyvarOccName (varSetElems tvs))