Source code snippets (examples)

Here are a few examples of using the Scala tabulate method, used to create and populate a List:

scala> val xs = List.tabulate(5)(_ + 1)
xs: List[Int] = List(1, 2, 3, 4, 5)

scala> val xs = List.tabulate(5)(_ + 2)
xs: List[Int] = List(2, 3, 4, 5, 6)

scala> val xs = List.tabulate(5)(_ * 2)
xs: List[Int] = List(0, 2, 4, 6, 8)

You can use the tabulate method on other Scala collections, including Array, Vector, Seq, and more:

scala> val xs = Array.tabulate(5)(_ * 2)
xs: Array[Int] = Array(0, 2, 4, 6, 8)

scala> val xs = Vector.tabulate(5)(_ * 2)
xs: scala.collection.immutable.Vector[Int] = Vector(0, 2, 4, 6, 8)

scala> val xs = Seq.tabulate(5)(_ * 2)
xs: Seq[Int] = List(0, 2, 4, 6, 8)

If you needed to see some examples of the tabulate method, I hope this has been helpful.

If you need to use MySQL or Postgresql dependency strings with Scala, SBT, build.sbt, or the Play Framework, these dependency settings work fine, as of October 9, 2012:

  "mysql" % "mysql-connector-java" % "5.1.18"

  "postgresql" % "postgresql" % "9.1-901.jdbc4"

I just started using the Play Framework 2 with MySQL, and because I use MAMP in my development environment, MySQL runs on port 8889, and not the MySQL default port of 3306. In short, to get the Play Framework to work with MySQL like this, I had to put these properties in the Play application.conf file:

db.default.url="jdbc:mysql://localhost:8889/finance"
db.default.driver=com.mysql.jdbc.Driver
db.default.user=root
db.default.pass=root

This is a little different than what the Play documentation looks like at the moment, but I can confirm that it works, letting me connect Play to MySQL on this different port.

In your build.sbt file, add this line to declare the Lift-JSON library to be a dependency in your Scala SBT project:

libraryDependencies += "net.liftweb" %% "lift-json" % "2.4-M5"

It's important to note that this line will vary depending on what version of Scala you are using. It's currently the correct dependency line for Scala 2.9.1.

See the URL for more information, or see this Lift-JSON URL:

https://github.com/lift/framework/blob/master/core/json/README.md

You can use the following curl script to POST JSON data to a web service:

curl \
  --header "Content-type: application/json" \
  --request POST \
  --data '{"symbol":"GOOG","price":"600.00"}' \
  http://localhost:8080/stocks/saveJsonStock

If you're familiar with the curl command, and JSON web services, this should make sense.

Here are links to other curl shell scripts I've written:

• How to view HTTP headers from the command line
• A curl shell script to download a URL and test website speed

For more information, see the (very long) curl man page.

I ran across this code snippet in the SBT docs, and thought it was a good but hard to find tip. To force/require a specific SBT version in a Scala/SBT project, include a line like the following in a file named build.properties in your project/ subdirectory:

sbt.version = 0.11.3

So, if your project directory is named /Users/Al/Foo, the file would be here:

/Users/Al/Foo/project/build.properties

I thought this tip was in the SBT FAQ, but at the moment I can't find it.

Q: How do I put comments in a Play Framework template? What is the syntax for Play Framework template comments?

A: Use @* ... *@, as shown here:

@*********************
 * This is a comment *
 *********************@

You can even use comments as the first line of Play Framework templates (before the function declaration):

@*************************************
 * The 'Hello, world' page           *
 *                                   *
 * @param msg The message to display *
 *************************************@
@(msg: String)

<h1>Hello, world</h1>

I got a "deprecation warnings; re-run with -deprecation for details" message from SBT when trying to compile or run my project code. How do I add -deprecation to see the deprecation warnings?

Add this entry to your SBT build.sbt file:

scalacOptions += "-deprecation"

For example, a complete build.sbt file might look like this:

name := "Test 1"

version := "1.0"

scalaVersion := "2.9.1"

resolvers += "Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"

libraryDependencies += "com.typesafe.akka" % "akka-actor" % "2.0.2"

scalacOptions += "-deprecation"