Add AbstractHole instances for Path, Scope, Address

Co-Authored-By: Rick Winfrey <rick.winfrey@gmail.com>

src/Data/Abstract/ScopeGraph.hs

@@ -24,6 +24,7 @@ module Data.Abstract.ScopeGraph
   , scopeOfRef
   ) where
 
+import Control.Abstract.Hole
 import           Data.Abstract.Name
 import qualified Data.Map.Strict as Map
 import           Data.Span
@@ -41,6 +42,15 @@ data Scope scopeAddress = Scope {
   , declarations :: Seq (Declaration, (Span, Maybe scopeAddress))
   } deriving (Eq, Show, Ord, Generic, NFData)
 
+instance Lower (Scope scopeAddress) where
+  lowerBound = Scope mempty mempty mempty
+
+instance AbstractHole (Scope scopeAddress) where
+  hole = lowerBound
+
+instance AbstractHole address => AbstractHole (Address address) where
+  hole = Address hole (Position 0)
+
 newtype Position = Position { unPosition :: Int }
   deriving (Eq, Show, Ord, Generic, NFData)
 
@@ -57,10 +67,14 @@ deriving instance NFData scope => NFData (ScopeGraph scope)
 
 data Path scope where
   -- | Construct a direct path to a declaration.
+  Hole :: Path scope
   DPath :: Declaration -> Position -> Path scope
   -- | Construct an edge from a scope to another declaration path.
   EPath :: EdgeLabel -> scope -> Path scope -> Path scope
 
+instance AbstractHole (Path scope) where
+  hole = Hole
+
 deriving instance Eq scope => Eq (Path scope)
 deriving instance Show scope => Show (Path scope)
 deriving instance Ord scope => Ord (Path scope)

src/Semantic/Graph.hs

@@ -422,17 +422,20 @@ resumingHeapError = runHeapErrorWith (\ baseError -> traceError "ScopeError" bas
 
 resumingScopeError :: ( Carrier sig m
                      , Member Trace sig
+                     , AbstractHole (Address address)
+                     , AbstractHole (Scope address)
+                     , AbstractHole (Path address)
+                     , AbstractHole address
                      , Show address
                      , Ord address
                      )
                     => Evaluator term address value (ResumableWithC (BaseError (ScopeError address)) (Eff m)) a
                     -> Evaluator term address value m a
 resumingScopeError = runScopeErrorWith (\ baseError -> traceError "ScopeError" baseError *> case baseErrorException baseError of
-  ex -> undefined)
+  ScopeError decl span -> pure hole
-  -- LookupError :: address -> HeapError address address
+  LookupScopeError -> pure hole
-  -- LookupLinksError :: address ->  HeapError address (Map EdgeLabel (Map address address))
+  LookupPathError decl -> pure hole
-  -- LookupPathError :: Path address ->  HeapError address address
+  CurrentScopeError -> pure hole)
-
 
 resumingTypeError :: ( Carrier sig m
                      , Member NonDet sig