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Merge pull request scala#2759 from sschaef/gh-pages
Add explanations about new REPL commands to feature list of 2.11
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‎2.11/index.markdown

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## REPL
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- @som-snytt added and improved several commands (:javap, :paste, :edit,...)
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- @folone and @eed3si9n contributed the `:kind` command to help to tell ground types from type constructors (#2340)
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- @rjolly made it possible to embed the repl as a JSR-223 Scripting Engine (#2206).
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The REPL is improved with several new commands that ease its usage. An overview of the commands can be seen by typing `:help` into the REPL.
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### `:paste` ([#2725](https://github.com/scala/scala/pull/2725))
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`:load` can only interpret a file from top to bottom which is for example a problem when there is a reference to a definition that is defined later. `:paste` is overworked to solve this limitation. It now can not only load a file but also handle it as a single unit.
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Contents of file `test.scala`:
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```scala
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// Foo has a companion object
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class Foo { private val foo = 7 }
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object Foo { def apply(f: Foo) = f.foo }
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Foo(new Foo)
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```
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REPL session:
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```scala
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scala> :paste test.scala
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Pasting file y.scala...
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defined class Foo
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defined object Foo
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res4: Int = 7
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```
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Theres is also the `-raw` option available, which denotes that the following is not a script anymore, but a normal Scala file:
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```scala
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scala> :paste -raw
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// Entering paste mode (ctrl-D to finish)
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package abc
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case class Foo(bar: Int)
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// Exiting paste mode, now interpreting.
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scala> abc.Foo(5)
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res5: abc.Foo = Foo(5)
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```
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Furthermore, there is a bug fixed that led to the problem that no error message is reported when the read code was incomplete ([#2672](https://github.com/scala/scala/pull/2672)).
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### `:save` ([#2697](https://github.com/scala/scala/pull/2697))
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With `:save` it is now possible to store the current REPL session to a file which allows one to extend the current state of the REPL at a later time:
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```scala
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scala> val i = 7
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i: Int = 7
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scala> val j = 8
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j: Int = 8
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scala> i*j
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res0: Int = 56
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scala> :save session.scala
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scala> :load session.scala
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Loading session.repl...
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i: Int = 7
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j: Int = 8
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res1: Int = 56
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```
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The `:save` command does only save the Scala commands to file not the full REPL output:
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```
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$ cat session.scala
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val i = 7
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val j = 8
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i*j
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```
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### `:settings` ([#2701](https://github.com/scala/scala/pull/2701))
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Sometimes one get warnings from the compiler about some code snippets. Previously it was needed to switch to `:power` mode in order to enable a full output of the warnings. Changing some other variables required a switch to the `:power` mode too. With this release it is possible to do this directly with the `:settings` command. By prefixing an property with a `+` sign the setting is enabled, an `-` disables it:
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```scala
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scala> new BigInt(java.math.BigInteger.TEN)
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res16: scala.math.BigInt = 10
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scala> new BigInt(java.math.BigInteger.TEN) {}
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warning: there were 1 deprecation warning(s); re-run with -deprecation for details
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res17: BigInt = 10
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scala> :settings +deprecation
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scala> new BigInt(java.math.BigInteger.TEN) {}
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<console>:11: warning: inheritance from class BigInt in package math is deprecated: This class will be made final.
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new BigInt(java.math.BigInteger.TEN) {}
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^
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res18: BigInt = 10
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scala> :settings -deprecation
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scala> new BigInt(java.math.BigInteger.TEN) {}
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res19: BigInt = 10
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```
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### `:edit` ([#2706](https://github.com/scala/scala/pull/2706))
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This command allows a user to change already inserted commands. It is possible to change a range of lines. The syntax is:
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- line number: 123 (only the line 123)
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- range: 123-130 (the lines 123 to 130)
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- offset: 123+7 (the lines 127 to 130)
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- remaining: 123- (all lines up from 123)
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- previous: -10 (the last ten lines)
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The environment variable EDITOR is used to specify the editor to invoke. If EDITOR is not set or if the `:line` command is used instead of `:edit`, the selected text is added to the end of the history in order to allow fast editing by navigating through the history with the arrow keys.
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```scala
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scala> :history
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<snip>
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2505 val i = 5
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2506 val j = 7
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2507 :history
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scala> :edit 2505+2
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+val i = 5
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+val j = 12
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i: Int = 5
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j: Int = 12
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scala> :history
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<snip>
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2505 val i = 5
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2506 val j = 7
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2507 :history
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2508 :edit 2505+2
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2509 val i = 5
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2510 val j = 12
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2511 :history
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```
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### `:javap` ([#1880](https://github.com/scala/scala/pull/1880))
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The command to dissasemble Java output got some bugfixes and new features. It is now possible to filter out members of classes:
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- `Bar#foo` filters out all `foo` members
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- `Bar#` filters out all `apply` members
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- `-fun Bar#foo` filters out all anonfuns of `foo` members
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- `-fun Bar#` filters out all anonfuns of `apply` members
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- `-app Bar` filters out `Bar.delayedInit`
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Example usage:
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```scala
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scala> object Foo { def apply = 10; def bar = 5 }
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defined object Foo
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scala> :javap Foo#bar
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public int bar();
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flags: ACC_PUBLIC
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Code:
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stack=1, locals=1, args_size=1
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0: iconst_5
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1: ireturn
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LocalVariableTable:
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Start Length Slot Name Signature
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0 2 0 this LFoo$;
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LineNumberTable:
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line 7: 0
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scala> :javap Foo#
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public int apply();
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flags: ACC_PUBLIC
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Code:
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stack=1, locals=1, args_size=1
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0: bipush 10
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2: ireturn
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LocalVariableTable:
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Start Length Slot Name Signature
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0 3 0 this LFoo$;
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LineNumberTable:
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line 7: 0
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```
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### `:kind` ([#2340](https://github.com/scala/scala/pull/2340))
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Because Scala supports working with higher kinded types, we might want to be able to inspects kinds as well as types:
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```scala
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scala> :kind Either
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scala.util.Either's kind is F[+A1,+A2]
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scala> :kind -v Either
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scala.util.Either's kind is F[+A1,+A2]
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* -(+)-> * -(+)-> *
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This is a type constructor: a 1st-order-kinded type.
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scala> :k -v Int
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scala.Int's kind is A
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*
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This is a proper type.
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scala> :k -v scala.Function1
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scala.Function1's kind is F[-A1,+A2]
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* -(-)-> * -(+)-> *
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This is a type constructor: a 1st-order-kinded type.
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```
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For a more detailful explanation on the notation see the discussion of the PR.
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### JSR-223 Scripting Engine support ([#2206](https://github.com/scala/scala/pull/2206))
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It is now possible to use the REPL as a Scripting Engine:
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```scala
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scala> import javax.script.ScriptEngineManager
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import javax.script.ScriptEngineManager
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scala> import scala.tools.nsc.interpreter.IMain
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import scala.tools.nsc.interpreter.IMain
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scala> val e = new ScriptEngineManager().getEngineByName("scala")
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e: javax.script.ScriptEngine = scala.tools.nsc.interpreter.IMain@7debe95d
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scala> e.put("n", 10)
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n: Object = 10
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scala> e.eval("1 to n.asInstanceOf[Int] foreach println")
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1
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res4: Object = null
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```

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