fix: issue #2 Join fails due to type confusion for String

.gitignore

@@ -1,2 +1,3 @@
+.bsp/
 .idea/
 target/

build.sbt

@@ -4,10 +4,10 @@ name := "crossbow"
 
 version := "0.1.5"
 
-scalaVersion := "2.13.3"
+scalaVersion := "2.13.6"
 crossScalaVersions := Seq(scalaVersion.value, "2.12.12", "2.11.12")
 
-scalacOptions += "-deprecation"
+scalacOptions ++= Seq("-deprecation", "-feature", "-language:existentials")
 
 libraryDependencies += "org.scala-lang" % "scala-reflect" % scalaVersion.value
 libraryDependencies += "org.scalatest" %% "scalatest-funsuite" % "3.2.0" % "test"
@@ -16,7 +16,7 @@ libraryDependencies += "org.scalatest" %% "scalatest-funsuite" % "3.2.0" % "test
  * Maven specific settings for publishing to Maven central.
  */
 publishMavenStyle := true
-publishArtifact in Test := false
+Test / publishArtifact := false
 pomIncludeRepository := { _ => false }
 publishTo := {
   val nexus = "https://oss.sonatype.org/"

project/build.properties

@@ -1 +1 @@
-sbt.version = 1.3.13
+sbt.version = 1.6.2

src/main/scala/com/audienceproject/crossbow/expr/package.scala

@@ -24,14 +24,29 @@ package object expr {
 
   case class AnyType(runtimeType: ru.Type) extends Type {
     override def toString: String = runtimeType.toString
+
+    override def equals(obj: Any): Boolean = obj match {
+      case AnyType(otherRuntimeType) => runtimeType =:= otherRuntimeType
+      case _ => false
+    }
   }
 
   case class ProductType(elementTypes: Type*) extends Type {
     override def toString: String = s"(${elementTypes.mkString(",")})"
+
+    override def equals(obj: Any): Boolean = obj match {
+      case ProductType(otherElementTypes@_*) => elementTypes == otherElementTypes
+      case _ => false
+    }
   }
 
   case class ListType(elementType: Type) extends Type {
     override def toString: String = s"List($elementType)"
+
+    override def equals(obj: Any): Boolean = obj match {
+      case ListType(otherElementType) => elementType == otherElementType
+      case _ => false
+    }
   }
 
 }

src/test/scala/com/audienceproject/crossbow/algorithms/SortMergeJoinTest.scala

@@ -46,4 +46,12 @@ class SortMergeJoinTest extends AnyFunSuite {
     assert(joined == expected)
   }
 
+  test("Join on scala.Predef.String and java.lang.String") {
+    case class Score(name: String, points: Int)
+    val scores = Seq(Score("abc", 20), Score("def", 40)).flatMap(Score.unapply).toDataFrame("name", "points")
+    val names = Seq("abc", "def").toDataFrame("name")
+    val joined = scores.join(names, $"name")
+    assert(joined.rowCount == 2)
+  }
+
 }