Implement BoxedRep proposalwip/boxed-rep

This implements the BoxedRep proposal, refactoring the `RuntimeRep`
hierarchy from:

```haskell
data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ...
```

to

```haskell
data RuntimeRep = BoxedRep Levity | ...
data Levity = Lifted | Unlifted
```

Updates binary, haddock submodules.

Closes #17526.

Metric Increase:
    T12545

1 files changed, 17 insertions, 4 deletions

diff --git a/libraries/ghc-prim/GHC/Types.hs b/libraries/ghc-prim/GHC/Types.hs
index f558619ac1..59edeec8af 100644
--- a/libraries/ghc-prim/GHC/Types.hs
+++ b/libraries/ghc-prim/GHC/Types.hs
@@ -33,7 +33,9 @@ module GHC.Types (
         Symbol,
         Any,
         type (~~), Coercible,
-        TYPE, RuntimeRep(..), Type, Constraint,
+        TYPE, Levity(..), RuntimeRep(..),
+        LiftedRep, UnliftedRep,
+        Type, UnliftedType, Constraint,
           -- The historical type * should ideally be written as
           -- `type *`, without the parentheses. But that's a true
           -- pain to parse, and for little gain.
@@ -85,8 +87,17 @@ type (->) = FUN 'Many
 -- | The kind of constraints, like @Show a@
 data Constraint
 
+-- | The runtime representation of lifted types.
+type LiftedRep = 'BoxedRep 'Lifted
+
+-- | The runtime representation of unlifted types.
+type UnliftedRep = 'BoxedRep 'Unlifted
+
 -- | The kind of types with lifted values. For example @Int :: Type@.
-type Type = TYPE 'LiftedRep
+type Type = TYPE LiftedRep
+
+-- | The kind of types with unlifted values. For example @Int# :: UnliftedType@.
+type UnliftedType = TYPE UnliftedRep
 
 data Multiplicity = Many | One
 
@@ -410,6 +421,8 @@ data SPEC = SPEC | SPEC2
 *                                                                      *
 ********************************************************************* -}
 
+-- | Whether a boxed type is lifted or unlifted.
+data Levity = Lifted | Unlifted
 
 -- | GHC maintains a property that the kind of all inhabited types
 -- (as distinct from type constructors or type-level data) tells us
@@ -425,8 +438,7 @@ data SPEC = SPEC | SPEC2
 data RuntimeRep = VecRep VecCount VecElem   -- ^ a SIMD vector type
                 | TupleRep [RuntimeRep]     -- ^ An unboxed tuple of the given reps
                 | SumRep [RuntimeRep]       -- ^ An unboxed sum of the given reps
-                | LiftedRep       -- ^ lifted; represented by a pointer
-                | UnliftedRep     -- ^ unlifted; represented by a pointer
+                | BoxedRep Levity -- ^ boxed; represented by a pointer
                 | IntRep          -- ^ signed, word-sized value
                 | Int8Rep         -- ^ signed,  8-bit value
                 | Int16Rep        -- ^ signed, 16-bit value
@@ -444,6 +456,7 @@ data RuntimeRep = VecRep VecCount VecElem   -- ^ a SIMD vector type
 -- RuntimeRep is intimately tied to TyCon.RuntimeRep (in GHC proper). See
 -- Note [RuntimeRep and PrimRep] in RepType.
 -- See also Note [Wiring in RuntimeRep] in GHC.Builtin.Types
+-- See also Note [TYPE and RuntimeRep] in GHC.Builtin.Type.Prim
 
 -- | Length of a SIMD vector type
 data VecCount = Vec2