init research

dataframe/plugins/kotlin-dataframe/testData/box/selectColsOf.kt

@@ -0,0 +1,23 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+@DataSchema
+interface JoinLeaf {
+    val something: Int
+    val somethingElse: String
+}
+
+@DataSchema
+interface Join2 {
+    val c: DataRow<JoinLeaf>
+}
+
+fun selectionDsl(df: DataFrame<Join2>) {
+    df.ungroup { c }.select { colsOf<String>() }.somethingElse
+}
+
+fun box(): String {
+    return "OK"
+}