Merge pull request #172 from Kotlin/seq-of

[Feature] Seq of functions

kotlin-spark-api/src/main/kotlin/org/jetbrains/kotlinx/spark/api/Seq.kt

@@ -0,0 +1,40 @@
+package org.jetbrains.kotlinx.spark.api
+
+import scala.collection.immutable.`Seq$`.`MODULE$` as Seq
+import scala.collection.immutable.Seq as Seq
+import scala.collection.mutable.`Seq$`.`MODULE$` as MutableSeq
+import scala.collection.mutable.Seq as MutableSeq
+
+/**
+ * Returns a new empty immutable Seq.
+ */
+fun <T> emptySeq(): Seq<T> = Seq.empty<T>() as Seq<T>
+
+/**
+ * Returns a new immutable Seq with the given elements.
+ */
+fun <T> seqOf(vararg elements: T): Seq<T> =
+    if (elements.isEmpty())
+        emptySeq()
+    else
+        Seq.newBuilder<T>().apply {
+            for (it in elements)
+                `$plus$eq`(it)
+        }.result() as Seq<T>
+
+/**
+ * Returns a new mutable Seq with the given elements.
+ */
+fun <T> emptyMutableSeq(): MutableSeq<T> = MutableSeq.empty<T>() as MutableSeq<T>
+
+/**
+ * Returns a new mutable Seq with the given elements.
+ */
+fun <T> mutableSeqOf(vararg elements: T): MutableSeq<T> =
+    if (elements.isEmpty())
+        emptyMutableSeq()
+    else
+        MutableSeq.newBuilder<T>().apply {
+            for (it in elements)
+                `$plus$eq`(it)
+        }.result() as MutableSeq<T>

kotlin-spark-api/src/test/kotlin/org/jetbrains/kotlinx/spark/api/ApiTest.kt

@@ -33,6 +33,18 @@ class ApiTest : ShouldSpec({
     context("miscellaneous integration tests") {
         withSpark(props = mapOf("spark.sql.codegen.comments" to true)) {
 
+            should("Create Seqs") {
+                spark.createDataset(seqOf(1, 2, 3), encoder())
+                    .collectAsList() shouldBe listOf(1, 2, 3)
+
+
+                seqOf(1, 2, 3) shouldBe seqOf(1, 2, 3)
+                mutableSeqOf(1, 2, 3) shouldBe mutableSeqOf(1, 2, 3)
+
+                seqOf<Int>() shouldBe emptySeq<Int>()
+                mutableSeqOf<Int>() shouldBe emptyMutableSeq<Int>()
+            }
+
             @OptIn(ExperimentalStdlibApi::class)
             should("broadcast variables") {
                 val largeList = (1..15).map { SomeClass(a = (it..15).toList().toIntArray(), b = it) }