https://github.com/vonzhou/programminginscala
Programming In Scala 3rd Examples.《Scala编程》第三版代码
https://github.com/vonzhou/programminginscala
functional-programming haskell java scala
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Programming In Scala 3rd Examples.《Scala编程》第三版代码
- Host: GitHub
- URL: https://github.com/vonzhou/programminginscala
- Owner: vonzhou
- Created: 2019-01-10T14:52:14.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2019-04-03T06:10:04.000Z (over 6 years ago)
- Last Synced: 2025-04-22T13:55:47.807Z (6 months ago)
- Topics: functional-programming, haskell, java, scala
- Language: Scala
- Homepage: https://github.com/vonzhou/learning-scala
- Size: 81.1 KB
- Stars: 7
- Watchers: 1
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Programming In Scala
脚本运行方式:
```
scala -nc hello.scala
```
类运行方式:
```
➜ ch04 git:(master) ✗ scalac ChecksumAccumulator.scala Summer.scala
➜ ch04 git:(master) ✗ scala ch04.Summer hello scala
hello: -20
scala: -4
```
## 1. A Scalable Language
语言命名
## 2. First Steps in Scala
写点脚本
## 3. Next Steps in Scala
使用List,Tuple,Set,Map
读文件
## 4. Classes and Objects
## 5. Basic Types and Operations
## 6. Functional Objects
## 7. Built-in Control Structures
## 8. Functions and Closures
## 9. Control Abstractions
## 10. Composition and Inheritance
## 11. Scala's Hierarchy
## 12. Traits
## 13. Packages and Imports
## 14. Assertions and Tests
## 15. Case Classes and Pattern Matching
## 16. Working with Lists
## 17. Working with other Collections
## 18. Mutable Objects
## 19. Type Parameterization
## 20. Abstract Members
```Scala
scala> trait Abstract {
| type T
|
| def transform(x: T): T
|
| val initial: T
|
| var current: T
| }
defined trait Abstract
scala> class Concrete extends Abstract {
| type T = String
|
| def transform(x: String) = x + x
|
| val initial = "hi"
| var current = initial
| }
defined class Concrete
scala>
scala> println(new Concrete().transform("vonzhou"))
vonzhouvonzhou
```
## 21. Implicit Conversions and Parameters
scala.Int:
```scala
import scala.language.implicitConversions
implicit def int2long(x: Int): Long = x.toLong
implicit def int2float(x: Int): Float = x.toFloat
implicit def int2double(x: Int): Double = x.toDouble
```
Predef:
```scala
implicit final class ArrowAssoc[A](private val self: A) extends AnyVal {
@inline def -> [B](y: B): Tuple2[A, B] = Tuple2(self, y)
def →[B](y: B): Tuple2[A, B] = ->(y)
}
```
## 22. Implementing Lists
2个子类：:: 和 Nil
covariant
```scala
val xs = List(1,2,3)
var ys:List[Any] = xs
println(ys)
```
List定义了3个抽象方法：
```scala
def isEmpty: Boolean
def head: A
def tail: List[A]
```
:: 方法的参数类型有一个lower bound，交互模式下运行：
```scala
scala> abstract class Fruit
defined class Fruit
scala> class Apple extends Fruit
defined class Apple
scala> class Orange extends Fruit
defined class Orange
scala> val apples = new Apple :: Nil
apples: List[Apple] = List(Apple@1224e1b6)
scala> val fruits = new Orange :: apples
fruits: List[Fruit] = List(Orange@61d09475, Apple@1224e1b6)
```
ListBuffer的实现：
```scala
def += (x: A): this.type = {
if (exported) copy()
if (isEmpty) {
last0 = new :: (x, Nil)
start = last0
} else {
val last1 = last0
last0 = new :: (x, Nil)
// 注意 :: 类构造器参数 tl 是var
last1.tl = last0
}
len += 1
this
}
```
> The design of Scala's List and ListBuffer is quite similar to what's done in Java's pair of classes String and StringBuffer.
## 23. For Expression Revisited
for 表达式最终都会被scala 编译器转换成map, flatMap, withFilter。
## 24. Collections in depth