Add HasCallStack to find and _class

Author: alt-romes

src/Data/Equality/Graph.hs

@@ -60,6 +60,8 @@ import Data.Equality.Graph.Lens
 
 import Data.Equality.Utils
 
+import GHC.Stack (HasCallStack)
+
 -- ROMES:TODO: join things built in paralell?
 -- instance Ord1 l => Semigroup (EGraph l) where
 --     (<>) eg1 eg2 = undefined -- not so easy
@@ -310,7 +312,7 @@ canonicalize (Node enode) eg = Node $ fmap (`find` eg) enode
 -- | Find the canonical representation of an e-class id in the e-graph
 --
 -- Invariant: The e-class id always exists.
-find :: ClassId -> EGraph a l -> ClassId
+find :: HasCallStack => ClassId -> EGraph a l -> ClassId
 find cid = findRepr cid . unionFind
 {-# INLINE find #-}
 

src/Data/Equality/Graph/Lens.hs

@@ -22,6 +22,8 @@ import Data.Equality.Graph.Nodes
 import Data.Equality.Graph.Classes
 import Data.Equality.Graph.ReprUnionFind
 
+import GHC.Stack (HasCallStack)
+
 -- | A 'Lens'' as defined in other lenses libraries
 type Lens' s a = forall f. Functor f => (a -> f a) -> (s -> f s)
 type Traversal s t a b = forall f. Applicative f => (a -> f b) -> (s -> f t)
@@ -39,7 +41,7 @@ type Traversal s t a b = forall f. Applicative f => (a -> f b) -> (s -> f t)
 -- | Lens for the e-class with the given id in an e-graph
 --
 -- Calls 'error' when the e-class doesn't exist
-_class :: ClassId -> Lens' (EGraph a l) (EClass a l)
+_class :: HasCallStack => ClassId -> Lens' (EGraph a l) (EClass a l)
 _class i afa s =
     let canon_id = findRepr i (unionFind s)
      in (\c' -> s { classes = IM.insert canon_id c' (classes s) }) <$> afa (classes s IM.! canon_id)

src/Data/Equality/Graph/ReprUnionFind.hs

@@ -21,6 +21,7 @@ import Data.Equality.Graph.Classes.Id
 
 import qualified Data.Equality.Utils.IntToIntMap as IIM
 import GHC.Exts ((+#), Int(..), Int#)
+import GHC.Stack (HasCallStack)
 
 type RUFSize = Int#
 
@@ -97,7 +98,8 @@ unionSets a b (RUF im si) = (a, RUF (IIM.insert b a im) si)
     -- new_hc = IM.adjust ((b:) . (represented_by_b <>)) a (IM.delete b hc)
 
 -- | Find the canonical representation of an e-class id
-findRepr :: ClassId -> ReprUnionFind
+findRepr :: HasCallStack
+         => ClassId -> ReprUnionFind
          -> ClassId -- ^ The found canonical representation
 #if __GLASGOW_HASKELL__ >= 902
 findRepr v@(I# v#) (RUF m s) =