--- a/src/main/scala/Main.scala	Fri Apr 02 19:47:48 2010 -0400
+++ b/src/main/scala/Main.scala	Fri Apr 02 20:04:36 2010 -0400
@@ -8,8 +8,10 @@
   case class Relation ( name:RelName, header:Header, body:Body )
   type Header = Map[AttrName, (LinkType, SQLDatatype)]
   type Body = Set[Tuple]
-  type Tuple = Map[AttrName, Either[LexicalValue, ☹]]
-  case class ☹ () // SQL NULL value
+  abstract class CellValue
+  case class LexicalValue (s:String) extends CellValue
+  case class ☹ () extends CellValue
+  type Tuple = Map[AttrName, CellValue]
   sealed abstract class LinkType
   case class Pk () extends LinkType
   case class Fk(r:Relation, a:AttrName) extends LinkType
@@ -19,7 +21,6 @@
   case class SQLInt () extends SQLDatatype
   type RelName = String
   type AttrName = String
-  type LexicalValue = String
 
   // RDF node types:
   type RDFGraph = Set[RDFTriple]
@@ -36,7 +37,7 @@
   def header (r:Relation) : Header = r.header
   def body (r:Relation) : Body = r.body
 
-  def lexvalue (h:Header, t:Tuple, a:AttrName) : Either[LexicalValue, ☹]
+  def lexvalue (h:Header, t:Tuple, a:AttrName) : CellValue
   = t(a)
   def sqlDatatype (h:Header, a:AttrName) : SQLDatatype = h(a)._2
   def linktype (h:Header, a:AttrName) : LinkType = h(a)._1
@@ -49,15 +50,15 @@
   def tuplemap (u:StemURI, t:Tuple, r:Relation) : Set[RDFTriple] = {
     val h = header(r)
     val k = pk(h)
-    val s = nodemap(u, r, k, lexvalue(h, t, k).left.get) // Assume: no NULLs in primary key
+    val s = nodemap(u, r, k, lexvalue(h, t, k).asInstanceOf[LexicalValue]) // Assume: no NULLs in primary key
     h.keysIterator.toList.flatMap(a => cellmap(u, r, a, s, t)).toSet
   }
 
   def cellmap (u:StemURI, r:Relation, a:AttrName, s:IRI, t:Tuple) : Option[RDFTriple] = {
     val h = header(r)
     lexvalue(h, t, a) match {
-      case Right(☹()) => None
-      case Left(l:LexicalValue) => {
+      case (☹()) => None
+      case l:LexicalValue => {
 	val p = predicatemap (u, r, a)
 	val o = linktype(h, a) match {
   	  case Fk(r2, a2) => IRIObject(nodemap(u, r2, a2, l))
@@ -69,7 +70,7 @@
   }
 
   def nodemap (u:StemURI, r:Relation, a:AttrName, l:LexicalValue) : IRI
-  = "<" + u + "/" + relname(r) + "/" + a + "." + l + "#foo>"
+  = "<" + u + "/" + relname(r) + "/" + a + "." + l.s + "#foo>"
   def predicatemap (u:StemURI, r:Relation, a:AttrName) : IRI
   = "<" + u + "/" + relname(r) + "#" + a + ">"
   def XSD (d:SQLDatatype) : IRI =
@@ -78,7 +79,7 @@
       case SQLInt() => "<http://www.w3.org/2001/XMLSchema#int>"
     }
   def literalmap (l:LexicalValue, d:SQLDatatype) : RDFLiteral
-  = "\"" + l + "\"^^" + XSD(d)
+  = "\"" + l.s + "\"^^" + XSD(d)
 
   // Utilities:
   def toSet[T](list: List[T]) = {

--- a/src/test/scala/Test.scala	Fri Apr 02 19:47:48 2010 -0400
+++ b/src/test/scala/Test.scala	Fri Apr 02 20:04:36 2010 -0400
@@ -8,20 +8,20 @@
 			     Map("ID" -> (Pk(), SQLInt()),
 				 "city" -> (NotLinked(), SQLString()),
 				 "state" -> (NotLinked(), SQLString())),
-			     Set(Map("ID" -> Left("18"),
-				     "city" -> Left("Cambridge"),
-				     "state" -> Left("MA"))))
+			     Set(Map("ID" -> LexicalValue("18"),
+				     "city" -> LexicalValue("Cambridge"),
+				     "state" -> LexicalValue("MA"))))
 
     val people = Relation("People",
 			     Map("ID" -> (Pk(), SQLInt()),
 				 "fname" -> (NotLinked(), SQLString()),
 				 "addr" -> (Fk(addresses, "ID"), SQLInt())),
-			     Set(Map("ID" -> Left("7"),
-				     "fname" -> Left("Bob"),
-				     "addr" -> Left("18")),
-				 Map("ID" -> Left("8"),
-				     "fname" -> Left("Sue"),
-				     "addr" -> Right(☹()))))
+			     Set(Map("ID" -> LexicalValue("7"),
+				     "fname" -> LexicalValue("Bob"),
+				     "addr" -> LexicalValue("18")),
+				 Map("ID" -> LexicalValue("8"),
+				     "fname" -> LexicalValue("Sue"),
+				     "addr" -> ☹())))
     val u:StemURI = "http://foo.example/DB"
     val expected:RDFGraph =
       Set(
@@ -35,7 +35,7 @@
 	RDFTriple("<http://foo.example/DB/Addresses/ID.18#foo>","<http://foo.example/DB/Addresses#city>",LiteralObject(""""Cambridge"^^<http://www.w3.org/2001/XMLSchema#string>""")),
 	RDFTriple("<http://foo.example/DB/Addresses/ID.18#foo>","<http://foo.example/DB/Addresses#state>",LiteralObject(""""MA"^^<http://www.w3.org/2001/XMLSchema#string>""")))
 
-    assert (expected == relationmap(u, people) ++ relationmap(u, addresses))
+    assert (expected === relationmap(u, people) ++ relationmap(u, addresses))
   }
 
 }