Merge pull request #1782 from doub1ejack/scala-en-repl

[scala/en] Added REPL basics to help people experiment as they learn.

1 files changed, 50 insertions, 10 deletions

diff --git a/scala.html.markdown b/scala.html.markdown
index 7f5f0ec3..5e3ece2d 100644
--- a/scala.html.markdown
+++ b/scala.html.markdown
@@ -12,22 +12,62 @@ Scala - the scalable language
 
 ```scala
 
+/////////////////////////////////////////////////
+// 0. Basics
+/////////////////////////////////////////////////
 /*
-  Set yourself up:
+  Setup Scala:
 
   1) Download Scala - http://www.scala-lang.org/downloads
   2) Unzip/untar to your favourite location and put the bin subdir in your `PATH` environment variable
-  3) Start a Scala REPL by running `scala`. You should see the prompt:
-
-  scala>
-
-  This is the so called REPL (Read-Eval-Print Loop). You may type any Scala
-  expression, and the result will be printed. We will explain what Scala files
-  look like further into this tutorial, but for now, let's start with some
-  basics.
-
 */
 
+/*
+  Try the REPL
+  
+  Scala has a tool called the REPL (Read-Eval-Print Loop) that is anologus to 
+  commandline interpreters in many other languages. You may type any Scala
+  expression, and the result will be evaluated and printed.  
+  
+  The REPL is a very handy tool to test and verify code.  Use it as you read 
+  this tutorial to quickly explore concepts on your own.
+*/
+  
+// Start a Scala REPL by running `scala`. You should see the prompt:
+$ scala
+scala>
+
+// By default each expression you type is saved as a new numbered value
+scala> 2 + 2
+res0: Int = 4
+
+// Default values can be reused.  Note the value type displayed in the result..
+scala> res0 + 2
+res1: Int = 6
+
+// Scala is a strongly typed language. You can use the REPL to check the type
+// without evaluating an expression.
+scala> :type (true, 2.0)
+(Boolean, Double)
+
+// REPL sessions can be saved 
+scala> :save /sites/repl-test.scala
+
+// Files can be loaded into the REPL
+scala> :load /sites/repl-test.scala
+Loading /sites/repl-test.scala...
+res2: Int = 4
+res3: Int = 6
+
+// You can search your recent history 
+scala> :h?
+1 2 + 2
+2 res0 + 2
+3 :save /sites/repl-test.scala
+4 :load /sites/repl-test.scala
+5 :h?
+
+// Now that you know how to play, let's learn a little scala...
 
 /////////////////////////////////////////////////
 // 1. Basics