chore: add Repr instance for Literal and Key

src/Lean/Expr.lean

@@ -11,7 +11,7 @@ namespace Lean
 inductive Literal where
   | natVal (val : Nat)
   | strVal (val : String)
-  deriving Inhabited, BEq
+  deriving Inhabited, BEq, Repr
 
 protected def Literal.hash : Literal → UInt64
   | Literal.natVal v => hash v

src/Lean/Meta/DiscrTreeTypes.lean

@@ -18,7 +18,7 @@ inductive Key where
   | star  : Key
   | other : Key
   | arrow : Key
-  deriving Inhabited, BEq
+  deriving Inhabited, BEq, Repr
 
 protected def Key.hash : Key → UInt64
   | Key.const n a => mixHash 5237 $ mixHash (hash n) (hash a)