Coercion Quantification

This patch corresponds to #15497.

According to https://ghc.haskell.org/trac/ghc/wiki/DependentHaskell/Phase2,
 we would like to have coercion quantifications back. This will
allow us to migrate (~#) to be homogeneous, instead of its current
heterogeneous definition. This patch is (lots of) plumbing only. There
should be no user-visible effects.

An overview of changes:

- Both `ForAllTy` and `ForAllCo` can quantify over coercion variables,
but only in *Core*. All relevant functions are updated accordingly.
- Small changes that should be irrelevant to the main task:
    1. removed dead code `mkTransAppCo` in Coercion
    2. removed out-dated Note Computing a coercion kind and
       roles in Coercion
    3. Added `Eq4` in Note Respecting definitional equality in
       TyCoRep, and updated `mkCastTy` accordingly.
    4. Various updates and corrections of notes and typos.
- Haddock submodule needs to be changed too.

Acknowledgments:
This work was completed mostly during Ningning Xie's Google Summer
of Code, sponsored by Google. It was advised by Richard Eisenberg,
supported by NSF grant 1704041.

Test Plan: ./validate

Reviewers: goldfire, simonpj, bgamari, hvr, erikd, simonmar

Subscribers: RyanGlScott, monoidal, rwbarton, carter

GHC Trac Issues: #15497

Differential Revision: https://phabricator.haskell.org/D5054

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/iface/ToIface.hs-boot b/compiler/iface/ToIface.hs-boot
index 46083f0414..e5f57ff9a3 100644
--- a/compiler/iface/ToIface.hs-boot
+++ b/compiler/iface/ToIface.hs-boot
@@ -3,14 +3,14 @@ module ToIface where
 import {-# SOURCE #-} TyCoRep
 import {-# SOURCE #-} IfaceType( IfaceType, IfaceTyCon, IfaceForAllBndr
                                , IfaceCoercion, IfaceTyLit, IfaceAppArgs )
-import Var ( TyVarBinder )
+import Var ( TyCoVarBinder )
 import TyCon ( TyCon )
 import VarSet( VarSet )
 
 -- For TyCoRep
 toIfaceTypeX :: VarSet -> Type -> IfaceType
 toIfaceTyLit :: TyLit -> IfaceTyLit
-toIfaceForAllBndr :: TyVarBinder -> IfaceForAllBndr
+toIfaceForAllBndr :: TyCoVarBinder -> IfaceForAllBndr
 toIfaceTyCon :: TyCon -> IfaceTyCon
 toIfaceTcArgs :: TyCon -> [Type] -> IfaceAppArgs
 toIfaceCoercionX :: VarSet -> Coercion -> IfaceCoercion