diff --git a/src/main/scala/singleton/ops/impl/GeneralMacros.scala b/src/main/scala/singleton/ops/impl/GeneralMacros.scala
index 6679139b..b868aea3 100644
--- a/src/main/scala/singleton/ops/impl/GeneralMacros.scala
+++ b/src/main/scala/singleton/ops/impl/GeneralMacros.scala
@@ -655,6 +655,13 @@ trait GeneralMacros {
   ////////////////////////////////////////////////////////////////////////
 
   def abort(msg: String, annotatedSym : Option[TypeSymbol] = defaultAnnotatedSym): Nothing = {
+    val st = java.lang.Thread.currentThread().getStackTrace()
+    println("\n\nstack trace:")
+    for { e <- st.filter(_.getClassName().startsWith("singleton")) } {
+      println(s"  $e")
+    }
+    println("\n")
+    //java.lang.Thread.dumpStack()
     VerboseTraversal(s"!!!!!!aborted with: $msg at $annotatedSym, $defaultAnnotatedSym")
     if (annotatedSym.isDefined) setAnnotation(msg, annotatedSym.get)
     c.abort(c.enclosingPosition, msg)
@@ -719,6 +726,7 @@ trait GeneralMacros {
   }
 
   def genOpTreeUnknown(opTpe : Type, calc : CalcUnknown) : Tree = {
+    println("In genOpTreeUnknown")
     val outTpe = calc.tpe
     calc.treeOption match {
       case Some(valueTree) =>
@@ -898,10 +906,17 @@ trait GeneralMacros {
     lazy val a = aCalc
     lazy val b = bCalc
     lazy val cArg = cCalc
+
     def unsupported() : Calc = {
-      (a, b) match {
-        case (aArg : CalcVal, bArg : CalcVal) => abort(s"Unsupported $funcType[$a, $b, $cArg]")
-        case _ => CalcUnknown(funcType.toType, None)
+      val itree = c.typecheck(q"implicitly[_root_.singleton.ops.impl.OpIntercept[${funcType.toType}, ${a.tpe}, ${b.tpe}, ${cArg.tpe}]]", silent = true)
+      if (itree != EmptyTree) {
+        println(s"\n\nitree= ${itree.tpe}\n\n")
+        CalcUnknown(itree.tpe, Some(itree))
+      } else {
+        (a, b) match {
+          case (aArg : CalcVal, bArg : CalcVal) => abort(s"Unsupported $funcType[$a, $b, $cArg]")
+          case _ => CalcUnknown(funcType.toType, None)
+        }
       }
     }
 
@@ -1375,6 +1390,9 @@ trait GeneralMacros {
       val funcType = opTpe.typeArgs.head.typeSymbol.asType
       val opResult = TypeCalc(opTpe)
 
+      println(s"usingFuncName: opTpe= $opTpe")
+      println(s"  funcType= $funcType")
+      println(s"  opResult= $opResult")
       val genTree = (funcType, opResult) match {
         case (funcTypes.ToNat, CalcLit.Int(t)) =>
           if (t < 0) abort(s"Nat cannot be a negative literal. Found: $t")
diff --git a/src/main/scala/singleton/ops/impl/OpMacros.scala b/src/main/scala/singleton/ops/impl/OpMacros.scala
index 3d8bb5c4..6a9c7413 100644
--- a/src/main/scala/singleton/ops/impl/OpMacros.scala
+++ b/src/main/scala/singleton/ops/impl/OpMacros.scala
@@ -1,6 +1,27 @@
 package singleton.ops.impl
 import scala.reflect.macros.whitebox
 
+
+trait OpIntercept[N, S1, S2, S3] extends OpMacro[N, S2, S2, S3] {
+  import singleton.ops.W
+
+  type OutWide = None.type
+  val valueWide: OutWide = None
+  val isLiteral: Boolean = false
+  type OutNat = shapeless.Nat._0
+  type OutChar = W.`'0'`.T
+  type OutInt = W.`0`.T
+  type OutLong = W.`0L`.T
+  type OutFloat = W.`0f`.T
+  type OutDouble = W.`0D`.T
+  type OutString = W.`""`.T
+  type OutBoolean = W.`false`.T
+}
+
+object OpIntercept {
+  type Aux[N, S1, S2, S3, O] = OpIntercept[N, S1, S2, S3] { type Out = O }
+}
+
 /********************************************************************************************************
   * Three arguments type function macro
   *******************************************************************************************************/
diff --git a/src/main/scala/singleton/ops/impl/TestRig.scala b/src/main/scala/singleton/ops/impl/TestRig.scala
new file mode 100644
index 00000000..809c215e
--- /dev/null
+++ b/src/main/scala/singleton/ops/impl/TestRig.scala
@@ -0,0 +1,39 @@
+package singleton.ops.impl
+
+import singleton.ops._
+
+trait Rig[V <: XInt] {
+  val value: Int
+  override def toString: String = s"Rig($value)"
+}
+
+object Rig {
+  // get the 'Out' type resulting from resolving an implicit type
+  object impeval {
+    trait Out[O]
+    def apply[I <: { type Out } ](implicit i: I): Out[i.Out] = new Out[i.Out] {}
+  }
+
+  implicit def rigAddition[L <: Rig[_], R <: Rig[_], O <: Rig[_]](implicit
+    add: Add.Aux[L, R, O]): OpIntercept.Aux[OpId.+, L, R, W.`0`.T, O] =
+      new OpIntercept[OpId.+, L, R, W.`0`.T] {
+        type Out = O
+        val value = add.value
+      }
+
+  trait Add[L, R] {
+    type Out
+    val value: Out
+  }
+  object Add {
+    type Aux[L, R, O] = Add[L, R] { type Out = O }
+
+    implicit def addRig[LV <: XInt, RV <: XInt, OV <: XInt](implicit
+        add: OpInt.Aux[LV + RV, OV]): Add.Aux[Rig[LV], Rig[RV], Rig[OV]] =
+      new Add[Rig[LV], Rig[RV]] {
+        type Out = Rig[OV]
+        val value = new Rig[OV] { val value = add.value }
+      }
+  }
+}
+