-//
-//extrPos :: Expr -> Pos
-//extrPos (VarExpr p _) = p
-//extrPos (Op2Expr p _ _ _) = p
-//extrPos (Op1Expr p _ _) = p
-//extrPos (IntExpr p _) = p
-//extrPos (CharExpr p _) = p
-//extrPos (BoolExpr p _) = p
-//extrPos (FunExpr p _) = p
-//extrPos (EmptyListExpr p) = p
-//extrPos (TupleExpr p _) = p