Upgrade to spark 2.4 (#40)

* Upgrade to Spark 2.4.
* Provide Databricks instructions.
* Prepare 0.4.0 release.

README.md

@@ -54,9 +54,14 @@ output.show(truncate = false)
 +----------------------------------------------+------------------------------------------------------+--------------------------------------------------+---------+
 ~~~
 
+### Databricks
+
+If you are a Databricks user, please follow the instructions in this
+[example notebook](https://databricks-prod-cloudfront.cloud.databricks.com/public/4027ec902e239c93eaaa8714f173bcfc/1233855/1962483213436895/588180/latest.html).
+
 ### Dependencies
 
-Because CoreNLP depends on `protobuf-java` 3.x but Spark 2.3 depends on `protobuf-java` 2.x,
+Because CoreNLP depends on `protobuf-java` 3.x but Spark 2.4 depends on `protobuf-java` 2.x,
 we release `spark-corenlp` as an assembly jar that includes CoreNLP as well as its transitive dependencies,
 except `protobuf-java` being shaded.
 This might cause issues if you have CoreNLP or its dependencies on the classpath.
@@ -67,7 +72,7 @@ To use `spark-corenlp`, you need one of the CoreNLP language models:
 # Download one of the language models. 
 wget http://repo1.maven.org/maven2/edu/stanford/nlp/stanford-corenlp/3.9.1/stanford-corenlp-3.9.1-models.jar
 # Run spark-shell 
-spark-shell --packages databricks/spark-corenlp:0.3.1-s_2.11 --jars stanford-corenlp-3.9.1-models.jar
+spark-shell --packages databricks/spark-corenlp:0.4.0-spark_2.4-scala_2.11 --jars stanford-corenlp-3.9.1-models.jar
 ~~~
 
 ### Acknowledgements

build.sbt

@@ -1,13 +1,18 @@
 import ReleaseTransformations._
 
+def majorVersion(version: String) = version.split('.').slice(0, 2).mkString(".")
+
 lazy val commonSettings = Seq(
   organization := "databricks",
   name := "spark-corenlp",
   spName := "databricks/spark-corenlp",
   licenses := Seq("GPL-3.0" -> url("http://opensource.org/licenses/GPL-3.0")),
   // dependency settings //
   scalaVersion := "2.11.8",
-  sparkVersion := "2.3.1",
+  sparkVersion := "2.4.0",
+  version := (version in ThisBuild).value +
+    s"-spark_${majorVersion(sparkVersion.value)}" +
+    s"-scala_${majorVersion(scalaVersion.value)}",
   initialize := {
     val _ = initialize.value
     // require Java 8+
@@ -21,7 +26,7 @@ lazy val commonSettings = Seq(
   fork in Test := true,
   javaOptions in Test ++= Seq("-Xmx6g"),
   // release settings //
-  spAppendScalaVersion := true,
+  spAppendScalaVersion := false,
   // We only use sbt-release to update version numbers for now.
   releaseProcess := Seq[ReleaseStep](
     inquireVersions,

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "0.3.2-SNAPSHOT"
+version in ThisBuild := "0.4.0-SNAPSHOT"