Split up `GHC.Core` somewhatwip/rules-module

- `GHC.Core.Annotated` now contains annotated Core

- `GHC.Core.Rules` now contains the rules definitions

- `GHC.Core.Orphans` now contains the orphans *something*

- `GHC.Core.Unfoldings` now contains the unfoldings defintions

- The old `GHC.Core.Rules`, which was about applying rules, is now
  `GHC.Core.Rules.Apply`. Compare with `GHC.Core.Simplify.Inlin` which was also
  about operations not the data structures and simple predictes
  themselves (which is `GHC.Core.Unfold`).

21 files changed, 44 insertions, 16 deletions

diff --git a/compiler/GHC/Core/Opt/Arity.hs b/compiler/GHC/Core/Opt/Arity.hs
index 5ed015281a..d8ad51a5c8 100644
--- a/compiler/GHC/Core/Opt/Arity.hs
+++ b/compiler/GHC/Core/Opt/Arity.hs
@@ -49,6 +49,8 @@ where
 import GHC.Prelude
 
 import GHC.Core
+import GHC.Core.Rules
+import GHC.Core.Unfoldings
 import GHC.Core.FVs
 import GHC.Core.Utils
 import GHC.Core.DataCon
diff --git a/compiler/GHC/Core/Opt/CSE.hs b/compiler/GHC/Core/Opt/CSE.hs
index 2f7718709a..4786275d2a 100644
--- a/compiler/GHC/Core/Opt/CSE.hs
+++ b/compiler/GHC/Core/Opt/CSE.hs
@@ -21,6 +21,7 @@ import GHC.Core.Utils   ( mkAltExpr
 import GHC.Core.FVs     ( exprFreeVars )
 import GHC.Core.Type    ( tyConAppArgs )
 import GHC.Core
+import GHC.Core.Unfoldings
 import GHC.Utils.Outputable
 import GHC.Types.Basic
 import GHC.Types.Tickish
diff --git a/compiler/GHC/Core/Opt/ConstantFold.hs b/compiler/GHC/Core/Opt/ConstantFold.hs
index 3d36368d5b..37c7c7d60f 100644
--- a/compiler/GHC/Core/Opt/ConstantFold.hs
+++ b/compiler/GHC/Core/Opt/ConstantFold.hs
@@ -43,6 +43,8 @@ import GHC.Types.Name ( Name, nameOccName )
 import GHC.Types.Basic
 
 import GHC.Core
+import GHC.Core.Rules
+import GHC.Core.Unfoldings
 import GHC.Core.Make
 import GHC.Core.SimpleOpt (  exprIsConApp_maybe, exprIsLiteral_maybe )
 import GHC.Core.DataCon ( DataCon,dataConTagZ, dataConTyCon, dataConWrapId, dataConWorkId )
diff --git a/compiler/GHC/Core/Opt/ConstantFold.hs-boot b/compiler/GHC/Core/Opt/ConstantFold.hs-boot
index 216af660ae..b47786ab03 100644
--- a/compiler/GHC/Core/Opt/ConstantFold.hs-boot
+++ b/compiler/GHC/Core/Opt/ConstantFold.hs-boot
@@ -1,8 +1,8 @@
 module GHC.Core.Opt.ConstantFold where
 
-import GHC.Prelude
-import GHC.Core
-import GHC.Builtin.PrimOps
-import GHC.Types.Name
+import GHC.Prelude ( Maybe )
+import GHC.Core.Rules( CoreRule )
+import GHC.Builtin.PrimOps ( PrimOp )
+import GHC.Types.Name ( Name )
 
 primOpRules ::  Name -> PrimOp -> Maybe CoreRule
diff --git a/compiler/GHC/Core/Opt/CprAnal.hs b/compiler/GHC/Core/Opt/CprAnal.hs
index 87d9eb2ec7..3d77c20fd8 100644
--- a/compiler/GHC/Core/Opt/CprAnal.hs
+++ b/compiler/GHC/Core/Opt/CprAnal.hs
@@ -27,6 +27,7 @@ import GHC.Core.DataCon
 import GHC.Core.Type
 import GHC.Core.Utils
 import GHC.Core
+import GHC.Core.Unfoldings
 import GHC.Core.Seq
 import GHC.Core.Opt.WorkWrap.Utils
 
diff --git a/compiler/GHC/Core/Opt/DmdAnal.hs b/compiler/GHC/Core/Opt/DmdAnal.hs
index fbe843cff8..ee4f0c4f33 100644
--- a/compiler/GHC/Core/Opt/DmdAnal.hs
+++ b/compiler/GHC/Core/Opt/DmdAnal.hs
@@ -19,6 +19,8 @@ import GHC.Prelude
 import GHC.Core.Opt.WorkWrap.Utils
 import GHC.Types.Demand   -- All of it
 import GHC.Core
+import GHC.Core.Rules
+import GHC.Core.Unfoldings
 import GHC.Core.Multiplicity ( scaledThing )
 import GHC.Utils.Outputable
 import GHC.Types.Var.Env
diff --git a/compiler/GHC/Core/Opt/Exitify.hs b/compiler/GHC/Core/Opt/Exitify.hs
index 6ad4614286..e56619877c 100644
--- a/compiler/GHC/Core/Opt/Exitify.hs
+++ b/compiler/GHC/Core/Opt/Exitify.hs
@@ -40,6 +40,7 @@ import GHC.Types.Var
 import GHC.Types.Id
 import GHC.Types.Id.Info
 import GHC.Core
+import GHC.Core.Annotated
 import GHC.Core.Utils
 import GHC.Utils.Monad.State.Strict
 import GHC.Builtin.Uniques
diff --git a/compiler/GHC/Core/Opt/FloatIn.hs b/compiler/GHC/Core/Opt/FloatIn.hs
index 2feef8a617..bbee9bb128 100644
--- a/compiler/GHC/Core/Opt/FloatIn.hs
+++ b/compiler/GHC/Core/Opt/FloatIn.hs
@@ -23,6 +23,7 @@ import GHC.Platform
 
 import GHC.Core
 import GHC.Core.Opt.Arity( isOneShotBndr )
+import GHC.Core.Annotated
 import GHC.Core.Make hiding ( wrapFloats )
 import GHC.Core.Utils
 import GHC.Core.FVs
diff --git a/compiler/GHC/Core/Opt/Monad.hs b/compiler/GHC/Core/Opt/Monad.hs
index d38f3e6c59..39e0ce791c 100644
--- a/compiler/GHC/Core/Opt/Monad.hs
+++ b/compiler/GHC/Core/Opt/Monad.hs
@@ -43,7 +43,7 @@ import GHC.Prelude hiding ( read )
 import GHC.Driver.Session
 import GHC.Driver.Env
 
-import GHC.Core.Rules     ( RuleBase, RuleEnv, mkRuleEnv )
+import GHC.Core.Rules.Apply ( RuleBase, RuleEnv, mkRuleEnv )
 import GHC.Core.Opt.Stats ( SimplCount, zeroSimplCount, plusSimplCount )
 
 import GHC.Types.Annotations
diff --git a/compiler/GHC/Core/Opt/OccurAnal.hs b/compiler/GHC/Core/Opt/OccurAnal.hs
index fc374adb99..0a69e27b5b 100644
--- a/compiler/GHC/Core/Opt/OccurAnal.hs
+++ b/compiler/GHC/Core/Opt/OccurAnal.hs
@@ -25,6 +25,8 @@ module GHC.Core.Opt.OccurAnal (
 import GHC.Prelude hiding ( head, init, last, tail )
 
 import GHC.Core
+import GHC.Core.Rules
+import GHC.Core.Unfoldings
 import GHC.Core.FVs
 import GHC.Core.Utils   ( exprIsTrivial, isDefaultAlt, isExpandableApp,
                           mkCastMCo, mkTicks )
diff --git a/compiler/GHC/Core/Opt/Pipeline.hs b/compiler/GHC/Core/Opt/Pipeline.hs
index 8be830dbeb..754d9776c3 100644
--- a/compiler/GHC/Core/Opt/Pipeline.hs
+++ b/compiler/GHC/Core/Opt/Pipeline.hs
@@ -21,8 +21,9 @@ import GHC.Driver.Config.Core.Rules ( initRuleOpts )
 import GHC.Platform.Ways  ( hasWay, Way(WayProf) )
 
 import GHC.Core
+import GHC.Core.Rules
 import GHC.Core.Opt.CSE  ( cseProgram )
-import GHC.Core.Rules   ( RuleBase, mkRuleBase, ruleCheckProgram, getRules )
+import GHC.Core.Rules.Apply    ( RuleBase, mkRuleBase, ruleCheckProgram, getRules )
 import GHC.Core.Ppr     ( pprCoreBindings )
 import GHC.Core.Utils   ( dumpIdInfoOfProgram )
 import GHC.Core.Lint    ( lintAnnots )
diff --git a/compiler/GHC/Core/Opt/SetLevels.hs b/compiler/GHC/Core/Opt/SetLevels.hs
index 95084cf7b6..51c171f438 100644
--- a/compiler/GHC/Core/Opt/SetLevels.hs
+++ b/compiler/GHC/Core/Opt/SetLevels.hs
@@ -66,6 +66,7 @@ module GHC.Core.Opt.SetLevels (
 import GHC.Prelude
 
 import GHC.Core
+import GHC.Core.Annotated
 import GHC.Core.Opt.Monad ( FloatOutSwitches(..) )
 import GHC.Core.Utils   ( exprType, exprIsHNF
                         , exprOkForSpeculation
@@ -81,6 +82,7 @@ import GHC.Core.Type    ( Type, tyCoVarsOfType
                         , mightBeUnliftedType, closeOverKindsDSet
                         , typeHasFixedRuntimeRep
                         )
+import GHC.Core.Unfoldings ( isStableUnfolding )
 import GHC.Core.Multiplicity     ( pattern ManyTy )
 
 import GHC.Types.Id
diff --git a/compiler/GHC/Core/Opt/Simplify.hs b/compiler/GHC/Core/Opt/Simplify.hs
index 7b7b439e33..d585af35a9 100644
--- a/compiler/GHC/Core/Opt/Simplify.hs
+++ b/compiler/GHC/Core/Opt/Simplify.hs
@@ -11,6 +11,7 @@ import GHC.Driver.Flags
 
 import GHC.Core
 import GHC.Core.Rules
+import GHC.Core.Rules.Apply
 import GHC.Core.Ppr     ( pprCoreBindings, pprCoreExpr )
 import GHC.Core.Opt.OccurAnal ( occurAnalysePgm, occurAnalyseExpr )
 import GHC.Core.Stats   ( coreBindsSize, coreBindsStats, exprSize )
@@ -22,6 +23,7 @@ import GHC.Core.Opt.Simplify.Env
 import GHC.Core.Opt.Simplify.Monad
 import GHC.Core.Opt.Stats ( simplCountN )
 import GHC.Core.FamInstEnv
+import GHC.Core.Unfoldings
 
 import GHC.Utils.Error  ( withTiming )
 import GHC.Utils.Logger as Logger
diff --git a/compiler/GHC/Core/Opt/Simplify/Inline.hs b/compiler/GHC/Core/Opt/Simplify/Inline.hs
index f91319e754..10b74be6a4 100644
--- a/compiler/GHC/Core/Opt/Simplify/Inline.hs
+++ b/compiler/GHC/Core/Opt/Simplify/Inline.hs
@@ -23,6 +23,7 @@ import GHC.Driver.Flags
 
 import GHC.Core
 import GHC.Core.Unfold
+import GHC.Core.Unfoldings
 import GHC.Types.Id
 import GHC.Types.Basic  ( Arity, RecFlag(..) )
 import GHC.Utils.Logger
diff --git a/compiler/GHC/Core/Opt/Simplify/Iteration.hs b/compiler/GHC/Core/Opt/Simplify/Iteration.hs
index e29581a2f0..6f917c3f8b 100644
--- a/compiler/GHC/Core/Opt/Simplify/Iteration.hs
+++ b/compiler/GHC/Core/Opt/Simplify/Iteration.hs
@@ -45,8 +45,10 @@ import GHC.Core.Opt.Arity ( ArityType, exprArity, arityTypeBotSigs_maybe
                           , typeArity, arityTypeArity, etaExpandAT )
 import GHC.Core.SimpleOpt ( exprIsConApp_maybe, joinPointBinding_maybe, joinPointBindings_maybe )
 import GHC.Core.FVs     ( mkRuleInfo )
-import GHC.Core.Rules   ( lookupRule, getRules )
+import GHC.Core.Rules
+import GHC.Core.Rules.Apply ( lookupRule, getRules )
 import GHC.Core.Multiplicity
+import GHC.Core.Unfoldings
 
 import GHC.Types.Literal   ( litIsLifted ) --, mkLitInt ) -- temporarily commented out. See #8326
 import GHC.Types.SourceText
diff --git a/compiler/GHC/Core/Opt/Simplify/Monad.hs b/compiler/GHC/Core/Opt/Simplify/Monad.hs
index 826c11f335..12e2338530 100644
--- a/compiler/GHC/Core/Opt/Simplify/Monad.hs
+++ b/compiler/GHC/Core/Opt/Simplify/Monad.hs
@@ -28,7 +28,7 @@ import GHC.Types.Id        ( Id, mkSysLocalOrCoVarM )
 import GHC.Types.Id.Info   ( IdDetails(..), vanillaIdInfo, setArityInfo )
 import GHC.Core.Type       ( Type, Mult )
 import GHC.Core.Opt.Stats
-import GHC.Core.Rules
+import GHC.Core.Rules.Apply
 import GHC.Core.Utils      ( mkLamTypes )
 import GHC.Types.Unique.Supply
 import GHC.Driver.Flags
diff --git a/compiler/GHC/Core/Opt/Simplify/Utils.hs b/compiler/GHC/Core/Opt/Simplify/Utils.hs
index 28b1ebc221..c4bf05a00a 100644
--- a/compiler/GHC/Core/Opt/Simplify/Utils.hs
+++ b/compiler/GHC/Core/Opt/Simplify/Utils.hs
@@ -45,6 +45,7 @@ module GHC.Core.Opt.Simplify.Utils (
 import GHC.Prelude hiding (head, init, last, tail)
 
 import GHC.Core
+import GHC.Core.Rules
 import GHC.Types.Literal ( isLitRubbish )
 import GHC.Core.Opt.Simplify.Env
 import GHC.Core.Opt.Simplify.Inline
@@ -54,10 +55,11 @@ import GHC.Core.Ppr
 import GHC.Core.TyCo.Ppr ( pprParendType )
 import GHC.Core.FVs
 import GHC.Core.Utils
-import GHC.Core.Rules( RuleEnv, getRules )
+import GHC.Core.Rules.Apply ( RuleEnv, getRules )
 import GHC.Core.Opt.Arity
 import GHC.Core.Unfold
 import GHC.Core.Unfold.Make
+import GHC.Core.Unfoldings
 import GHC.Core.Opt.Simplify.Monad
 import GHC.Core.Type     hiding( substTy )
 import GHC.Core.Coercion hiding( substCo )
@@ -1065,7 +1067,7 @@ including those in the LHS of rules.
 This can cause somewhat surprising results; for instance, in #18162 we found
 that a rule template contained ticks in its arguments, because
 postInlineUnconditionally substituted in a trivial expression that contains
-ticks. See Note [Tick annotations in RULE matching] in GHC.Core.Rules for
+ticks. See Note [Tick annotations in RULE matching] in GHC.Core.Rules.Apply for
 details.
 
 Note [Cast swizzling on rule LHSs]
diff --git a/compiler/GHC/Core/Opt/SpecConstr.hs b/compiler/GHC/Core/Opt/SpecConstr.hs
index 6a45129f06..4b10a924af 100644
--- a/compiler/GHC/Core/Opt/SpecConstr.hs
+++ b/compiler/GHC/Core/Opt/SpecConstr.hs
@@ -29,6 +29,7 @@ import GHC.Driver.Session ( DynFlags(..), GeneralFlag( Opt_SpecConstrKeen )
                           , gopt, hasPprDebug )
 
 import GHC.Core
+import GHC.Core.Rules
 import GHC.Core.Subst
 import GHC.Core.Utils
 import GHC.Core.Unfold
@@ -40,8 +41,9 @@ import GHC.Core.Opt.OccurAnal( scrutBinderSwap_maybe )
 import GHC.Core.DataCon
 import GHC.Core.Class( classTyVars )
 import GHC.Core.Coercion hiding( substCo )
-import GHC.Core.Rules
+import GHC.Core.Rules.Apply
 import GHC.Core.Predicate ( typeDeterminesValue )
+import GHC.Core.Unfoldings
 import GHC.Core.Type     hiding ( substTy )
 import GHC.Core.TyCon   (TyCon, tyConName )
 import GHC.Core.Multiplicity
@@ -2586,19 +2588,19 @@ argToPat1 env in_scope val_env (Tick _ arg) arg_occ arg_str
         -- Ignore Notes.  In particular, we want to ignore any InlineMe notes
         -- Perhaps we should not ignore profiling notes, but I'm going to
         -- ride roughshod over them all for now.
-        --- See Note [Tick annotations in RULE matching] in GHC.Core.Rules
+        --- See Note [Tick annotations in RULE matching] in GHC.Core.Rules.Apply
 
 argToPat1 env in_scope val_env (Let _ arg) arg_occ arg_str
   = argToPat env in_scope val_env arg arg_occ arg_str
-        -- See Note [Matching lets] in "GHC.Core.Rules"
+        -- See Note [Matching lets] in "GHC.Core.Rules.Apply"
         -- Look through let expressions
         -- e.g.         f (let v = rhs in (v,w))
         -- Here we can specialise for f (v,w)
         -- because the rule-matcher will look through the let.
 
-{- Disabled; see Note [Matching cases] in "GHC.Core.Rules"
+{- Disabled; see Note [Matching cases] in "GHC.Core.Rules.Apply"
 argToPat env in_scope val_env (Case scrut _ _ [(_, _, rhs)]) arg_occ
-  | exprOkForSpeculation scrut  -- See Note [Matching cases] in "GHC.Core.Rules"
+  | exprOkForSpeculation scrut  -- See Note [Matching cases] in "GHC.Core.Rules.Apply"
   = argToPat env in_scope val_env rhs arg_occ
 -}
 
@@ -2702,7 +2704,7 @@ argToPat1 env in_scope val_env (Var v) arg_occ arg_str
 --      And by not wild-carding we tend to get forall'd
 --      variables that are in scope, which in turn can
 --      expose the weakness in let-matching
---      See Note [Matching lets] in GHC.Core.Rules
+--      See Note [Matching lets] in GHC.Core.Rules.Apply
 
   -- Check for a variable bound inside the function.
   -- Don't make a wild-card, because we may usefully share
diff --git a/compiler/GHC/Core/Opt/Specialise.hs b/compiler/GHC/Core/Opt/Specialise.hs
index dda10da34e..d9f9f7e38e 100644
--- a/compiler/GHC/Core/Opt/Specialise.hs
+++ b/compiler/GHC/Core/Opt/Specialise.hs
@@ -27,6 +27,8 @@ import GHC.Core
 import GHC.Core.Make      ( mkLitRubbish )
 import GHC.Core.Unify     ( tcMatchTy )
 import GHC.Core.Rules
+import GHC.Core.Rules.Apply
+import GHC.Core.Unfoldings
 import GHC.Core.Utils     ( exprIsTrivial
                           , mkCast, exprType
                           , stripTicksTop, mkInScopeSetBndrs )
diff --git a/compiler/GHC/Core/Opt/WorkWrap.hs b/compiler/GHC/Core/Opt/WorkWrap.hs
index 29f1e3973f..aefbafe03c 100644
--- a/compiler/GHC/Core/Opt/WorkWrap.hs
+++ b/compiler/GHC/Core/Opt/WorkWrap.hs
@@ -14,6 +14,7 @@ where
 import GHC.Prelude
 
 import GHC.Core
+import GHC.Core.Rules
 import GHC.Core.Unfold.Make
 import GHC.Core.Utils  ( exprType, exprIsHNF )
 import GHC.Core.Type
diff --git a/compiler/GHC/Core/Opt/WorkWrap/Utils.hs b/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
index f599975355..b45fb1210b 100644
--- a/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
+++ b/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
@@ -22,6 +22,7 @@ where
 import GHC.Prelude
 
 import GHC.Core
+import GHC.Core.Unfoldings
 import GHC.Core.Utils
 import GHC.Core.DataCon
 import GHC.Core.Make