Explicitly use scala.collection.Seq to allow use of mutable collections in Scala 2.13

core/shared/src/main/scala-2.12/plotly/MutableSequenceImplicitConversions.scala

@@ -0,0 +1,5 @@
+package plotly
+
+trait MutableSequenceImplicitConversions {
+  // Unneccessary in Scala 2.12, since the `Seq` alias refers to the supertype for mutable and immutable sequences
+}

core/shared/src/main/scala-2.13/plotly/MutableSequenceImplicitConversions.scala

@@ -0,0 +1,26 @@
+package plotly
+
+import plotly.Sequence.{DateTimes, Doubles, NestedDoubles, NestedInts, Strings}
+import plotly.element.LocalDateTime
+import scala.collection.{Seq => BaseScalaSeq}
+
+trait MutableSequenceImplicitConversions {
+
+  implicit def fromMutableDoubleSeq(s: BaseScalaSeq[Double]): Sequence =
+    Doubles(s.toSeq)
+  implicit def fromMutableFloatSeq(s: BaseScalaSeq[Float]): Sequence =
+    Doubles(s.map(_.toDouble).toSeq)
+  implicit def fromMutableIntSeq(s: BaseScalaSeq[Int]): Sequence =
+    Doubles(s.map(_.toDouble).toSeq)
+  implicit def fromMutableLongSeq(s: BaseScalaSeq[Long]): Sequence =
+    Doubles(s.map(_.toDouble).toSeq)
+  implicit def fromMutableNestedDoubleSeq(s: BaseScalaSeq[BaseScalaSeq[Double]]): Sequence =
+    NestedDoubles(s.map(_.toSeq).toSeq)
+  implicit def fromMutableNestedIntSeq(s: BaseScalaSeq[BaseScalaSeq[Int]]): Sequence =
+    NestedInts(s.map(_.toSeq).toSeq)
+  implicit def fromMutableStringSeq(s: BaseScalaSeq[String]): Sequence =
+    Strings(s.toSeq)
+  implicit def fromMutableDateTimes(seq: BaseScalaSeq[LocalDateTime]): Sequence =
+    DateTimes(seq.toSeq)
+
+}

core/shared/src/main/scala/plotly/Sequence.scala

@@ -4,7 +4,7 @@ import plotly.element.LocalDateTime
 
 sealed abstract class Sequence extends Product with Serializable
 
-object Sequence {
+object Sequence extends MutableSequenceImplicitConversions {
   final case class Doubles(seq: Seq[Double]) extends Sequence
   final case class NestedDoubles(seq: Seq[Seq[Double]]) extends Sequence
   final case class NestedInts(seq: Seq[Seq[Int]]) extends Sequence

tests/src/test/scala/plotly/SequenceTests.scala

@@ -0,0 +1,31 @@
+package plotly
+
+import org.scalatest.FlatSpec
+
+import scala.collection.mutable.ArrayBuffer
+
+class SequenceTests extends FlatSpec {
+
+  "The implicit sequence conversion" should "convert a List to a Sequence" in {
+    assert((List(1, 2, 3): Sequence) === Sequence.Doubles(List(1d, 2d, 3d)))
+  }
+
+  it should "convert a mutable ArrayBuffer to a Sequence" in {
+    assert((ArrayBuffer(1, 2, 3): Sequence) === Sequence.Doubles(List(1d, 2d, 3d)))
+  }
+
+  it should "convert a nested mutable ArrayBuffer to a Sequence" in {
+    val mutableNestedDoubles: ArrayBuffer[ArrayBuffer[Double]] = ArrayBuffer(
+      ArrayBuffer(1d, 2d),
+      ArrayBuffer(3d, 4d),
+    )
+
+    val nestedDoublesList: List[List[Double]] = List(
+      List(1d, 2d),
+      List(3d, 4d),
+    )
+
+    assert((mutableNestedDoubles: Sequence) === Sequence.NestedDoubles(nestedDoublesList))
+  }
+
+}