make sure to adjust nullability in order to fix platform types

Platform types can lead to unexpected NPE and the way types rendered now, "URI!" ! sign appears. Code with such type cannot be compiled
Given type URI!, type.withNullability will produce either URI or URI?. Both are OK for us.

Author: koperagen

core/generated-sources/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/TypeConversions.kt

@@ -253,7 +253,7 @@ public fun NullabilityOptions.applyNullability(data: List<Any?>, expectedNulls:
 
 public inline fun <reified T> Iterable<T>.toColumn(
     name: String = "",
-    infer: Infer = Infer.None,
+    infer: Infer = Infer.Nulls,
 ): DataColumn<T> =
     (
         if (infer == Infer.Type) DataColumn.createWithTypeInference(name, asList())

core/generated-sources/src/test/kotlin/org/jetbrains/kotlinx/dataframe/columns/DataColumns.kt

@@ -0,0 +1,31 @@
+package org.jetbrains.kotlinx.dataframe.columns
+
+import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.api.toColumn
+import org.jetbrains.kotlinx.dataframe.api.toDataFrame
+import org.junit.Test
+import java.net.URI
+
+class DataColumns {
+    @Test
+    fun `create column with platform type from Api`() {
+        val df1 = listOf(1, 2, 3).toDataFrame {
+            expr { URI.create("http://example.com") } into "text"
+        }
+        df1["text"].type().toString() shouldBe "java.net.URI"
+    }
+
+    @Test
+    fun `create column with nullable platform type from Api`() {
+        val df1 = listOf(1, 2, 3).toDataFrame {
+            expr { i -> URI.create("http://example.com").takeIf { i == 2 } } into "text"
+        }
+        df1["text"].type().toString() shouldBe "java.net.URI?"
+    }
+
+    @Test
+    fun `create column with nullable platform type from factory method`() {
+        val col = listOf(URI.create("http://example.com"), null).toColumn("a")
+        col.type().toString() shouldBe "java.net.URI?"
+    }
+}

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/TypeConversions.kt

@@ -253,7 +253,7 @@ public fun NullabilityOptions.applyNullability(data: List<Any?>, expectedNulls:
 
 public inline fun <reified T> Iterable<T>.toColumn(
     name: String = "",
-    infer: Infer = Infer.None,
+    infer: Infer = Infer.Nulls,
 ): DataColumn<T> =
     (
         if (infer == Infer.Type) DataColumn.createWithTypeInference(name, asList())

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/columns/DataColumns.kt

@@ -0,0 +1,31 @@
+package org.jetbrains.kotlinx.dataframe.columns
+
+import io.kotest.matchers.shouldBe
+import org.jetbrains.kotlinx.dataframe.api.toColumn
+import org.jetbrains.kotlinx.dataframe.api.toDataFrame
+import org.junit.Test
+import java.net.URI
+
+class DataColumns {
+    @Test
+    fun `create column with platform type from Api`() {
+        val df1 = listOf(1, 2, 3).toDataFrame {
+            expr { URI.create("http://example.com") } into "text"
+        }
+        df1["text"].type().toString() shouldBe "java.net.URI"
+    }
+
+    @Test
+    fun `create column with nullable platform type from Api`() {
+        val df1 = listOf(1, 2, 3).toDataFrame {
+            expr { i -> URI.create("http://example.com").takeIf { i == 2 } } into "text"
+        }
+        df1["text"].type().toString() shouldBe "java.net.URI?"
+    }
+
+    @Test
+    fun `create column with nullable platform type from factory method`() {
+        val col = listOf(URI.create("http://example.com"), null).toColumn("a")
+        col.type().toString() shouldBe "java.net.URI?"
+    }
+}