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 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Automatically generated Scala interpreter transcript from:
 *
 * Programming in Scala (Fifth Edition)
 * by Martin Odersky, Lex Spoon, Bill Venners, and Frank Sommers
 *
 * http://booksites.artima.com/programming_in_scala_5ed
 */


scala>   trait Expr
           case class Var(name: String) extends Expr
         case class Num(number: Double) extends Expr
         case class UnOp(operator: String, arg: Expr) extends Expr
         case class BinOp(operator: String, 
             left: Expr, right: Expr) extends Expr

defined trait Expr
defined class Var
defined class Num
defined class UnOp
defined class BinOp

scala>   def simplifyTop(expr: Expr): Expr =
           expr match
             case UnOp("-", UnOp("-", e))  => e // Double negation
             case BinOp("+", e, Num(0)) => e // Adding zero
             case BinOp("*", e, Num(1)) => e // Multiplying by one
             case _ => expr

                    case UnOp("-", UnOp("-", e))  => e // Double negation
                    ^
On line 3: error: '{' expected but 'case' found.
                    case BinOp("+", e, Num(0)) => e // Adding zero
                    ^
On line 4: error: illegal start of definition
                    case BinOp("*", e, Num(1)) => e // Multiplying by one
                    ^
On line 5: error: illegal start of definition
                    case _ => expr
                    ^
On line 6: error: illegal start of definition

scala> simplifyTop(UnOp("-", UnOp("-", Var("x"))))
       ^
       error: not found: value simplifyTop

scala>   def describe(x: Any) =
           x match
             case 5 => "five"
             case true => "truth"
             case "hello" => "hi!"
             case Nil => "the empty list"
             case _ => "something else"

                    case 5 => "five"
                    ^
On line 3: error: '{' expected but 'case' found.
                    case true => "truth"
                    ^
On line 4: error: illegal start of definition
                    case "hello" => "hi!"
                    ^
On line 5: error: illegal start of definition
                    case Nil => "the empty list"
                    ^
On line 6: error: illegal start of definition
                    case _ => "something else"
                    ^
On line 7: error: illegal start of definition

scala> import math.{E, Pi}
import math.{E, Pi}

scala> E match
         case Pi => s"strange math? Pi = $Pi"
         case _ => "OK"
         case Pi => s"strange math? Pi = $Pi"
         ^
On line 2: error: '{' expected but 'case' found.
         case _ => "OK"
         ^
On line 3: error: illegal start of definition

scala> val pi = math.Pi
pi: Double = 3.141592653589793

scala> E match
         case pi => s"strange math? Pi = $pi"
         case pi => s"strange math? Pi = $pi"
         ^
On line 2: error: '{' expected but 'case' found.

scala> E match
         case pi => s"strange math? Pi = $pi"
         case _ => "OK"  
         case pi => s"strange math? Pi = $pi"
         ^
On line 2: error: '{' expected but 'case' found.
         case _ => "OK"
         ^
On line 3: error: illegal start of definition

scala> E match
         case `pi` => s"strange math? Pi = $pi"
         case _ => "OK"
         case `pi` => s"strange math? Pi = $pi"
         ^
On line 2: error: '{' expected but 'case' found.
         case _ => "OK"
         ^
On line 3: error: illegal start of definition

scala>   def tupleDemo(obj: Any) =
           obj match
             case (a, b, c) => s"matched $a$b$c"
             case _ => ""

                    case (a, b, c) => s"matched $a$b$c"
                    ^
On line 3: error: '{' expected but 'case' found.
                    case _ => ""
                    ^
On line 4: error: illegal start of definition

scala>   def generalSize(x: Any) =
           x match
             case s: String => s.length
             case m: Map[_, _] => m.size
             case _ => -1

                    case s: String => s.length
                    ^
On line 3: error: '{' expected but 'case' found.
                    case m: Map[_, _] => m.size
                    ^
On line 4: error: illegal start of definition
                    case _ => -1
                    ^
On line 5: error: illegal start of definition

scala> 3: String // ': String' is the type ascription
       ^
       error: type mismatch;
        found   : Int(3)
        required: String

scala> Var("x"): Expr // Expr is a supertype of Var
res2: Expr = Var(x)

scala> 3: Long
res3: Long = 3

scala> def isIntIntMap(x: Any) =
         x match
           case m: Map[Int, Int] => true
           case _ => false
       
           case m: Map[Int, Int] => true
           ^
On line 3: error: '{' expected but 'case' found.
           case _ => false
           ^
On line 4: error: illegal start of definition

scala> def simplifyAdd(e: Expr) =
         e match
           case BinOp("+", x, x) => BinOp("*", x, Num(2))
           case _ => e
       
           case BinOp("+", x, x) => BinOp("*", x, Num(2))
           ^
On line 3: error: '{' expected but 'case' found.
           case _ => e
           ^
On line 4: error: illegal start of definition

scala> def simplifyBad(expr: Expr): Expr =                                      
         expr match
           case UnOp(op, e) => UnOp(op, simplifyBad(e))
           case UnOp("-", UnOp("-", e)) => e
           case _ => expr
       
           case UnOp(op, e) => UnOp(op, simplifyBad(e))
           ^
On line 3: error: '{' expected but 'case' found.
           case UnOp("-", UnOp("-", e)) => e
           ^
On line 4: error: illegal start of definition
           case _ => expr
           ^
On line 5: error: illegal start of definition

scala>     sealed trait Expr
         case class Var(name: String) extends Expr
         case class Num(number: Double) extends Expr
         case class UnOp(operator: String, arg: Expr) extends Expr
         case class BinOp(operator: String, 
             left: Expr, right: Expr) extends Expr

defined trait Expr
defined class Var
defined class Num
defined class UnOp
defined class BinOp

scala>   def describe(e: Expr): String = 
           e match
             case Num(_) => "a number"
             case Var(_) => "a variable"

                    case Num(_) => "a number"
                    ^
On line 3: error: '{' expected but 'case' found.
                    case Var(_) => "a variable"
                    ^
On line 4: error: illegal start of definition

scala> val myTuple = (123, "abc")
myTuple: (Int, String) = (123,abc)

scala> val (number, string) = myTuple
number: Int = 123
string: String = abc

scala> val exp = new BinOp("*", Num(5), Num(1))
exp: BinOp = BinOp(*,Num(5.0),Num(1.0))

scala> val BinOp(op, left, right) = exp
op: String = *
left: Expr = Num(5.0)
right: Expr = Num(1.0)

scala>   val withDefault: Option[Int] => Int =
           case Some(x) => x
           case None => 0

                  case Some(x) => x
                  ^
On line 2: error: illegal start of simple expression
                  case None => 0
                  ^
On line 3: error: illegal start of definition

scala>   val second: List[Int] => Int =
           case x :: y :: _ => y

                  case x :: y :: _ => y
                  ^
On line 2: error: illegal start of simple expression

scala>   val second: PartialFunction[List[Int],Int] =
           case x :: y :: _ => y

                  case x :: y :: _ => y
                  ^
On line 2: error: illegal start of simple expression