crude but effective stratification

lib/Quox/Parser/FromParser/Error.idr

@@ -24,6 +24,7 @@ data Error =
   | DimNotInScope Loc PBaseName
   | QtyNotGlobal Loc Qty
   | DimNameInTerm Loc PBaseName
+  | DisplacedBoundVar Loc PName
   | WrapTypeError TypeError
   | LoadError Loc String FileError
   | WrapParseError String ParseError
@@ -89,6 +90,11 @@ parameters (showContext : Bool)
       (sep ["dimension" <++> !(hl DVar $ text i),
             "used in a term context"])
 
+  prettyError (DisplacedBoundVar loc x) = pure $
+    vappend !(prettyLoc loc)
+      (sep ["local variable" <++> !(hl TVar $ text $ toDotsP x),
+            "cannot be displaced"])
+
   prettyError (WrapTypeError err) =
     Typing.prettyError showContext $ trimContext 2 err