edx scala

Short form of function text Scala provides a number of ways to remove redundant information and write the function text more briefly. Pay attention to these opportunities because they allow you to get rid of the clutter in your code. One way to make the text of a function shorter is to remove the parameter type. Therefore, the previous example with a filter can be written like this: scala>　someNumbers.fi

Fuzzy concept list method and function covariant and contravariant lambda trait and Interface Curry Extractor object case-defined class-biased function implicit conversion and implicit parameter call-by namecall-by value Fuzzy Concept list First record, follow-up after the focus of the breach method and function covariant and inverse lambda what exactly is the difference between trait and interface currying (currying) Extractor object implicit conversion and implicit argument case definition cla

Map Construction Map Immutable: Val map = map ("sa"-> 1, "S"-> 2)Map ("sa") = 3 // Error Val emptymap = new scala. collection. Immutable. hashmap [String, int] Variable: Val MAP2 = scala. collection. mutable. Map ("sa"-> 2)MAP2 ("sa") = 3 Val emptymap = new scala. collection. mutable. hashmap [String, int] Note:-> used to create tuples, "sa"-> 1 ("sa", 1) Initial

Install Scala 2.10.x in Ubuntu The default scala version on Ubuntu 14.04.1 LTS is 2.9, while the latest spark-1.3 requires the lowest version of scala 2.10.x, first, use apt-get remove scala to clear old scala versions on the machine. Download the http://www.scala-lang.org/

Mainly from the Coursera course "functional programming Principles in Scala"by Professor Martin Odersky, the inventor of the Scala language. 3. Data and Abstraction3.1 Class hierarchiesThis set of subtitles is out -,- of sync, listening to a little effort!The concept of a class is similar to that of other languages, such as base class, subclass, and parent class. In

Scala list faq:how do I add elements to a scala list?This was actually a trick question, because you can ' t add elements to a scalalist; It's an immutable data structure, like a Java String .prepending elements to Scala ListsOne thing you can does when working with a Scala was to List create a new from an List existin

Scala 学习One: Environment configurationScale official website address: http://scala-ide.org/download/sdk.html1: Install Java JDK2: Install Scala3: Install the Scala integrated IDESecond: Start the Scala learning journeyHello Scala Demo1: Create a new

We know that the IDE has a number of selected versions for development. As most of us often use is as follows.Eclipse * VersionEclipse * DownloadAnd we know that for the Scala development of Spark, there's a specially designed eclipse for it,Scala IDE for Eclipse　　1. Scala IDE for eclipse downloadhttp://scala-ide.org/

(Environment: Jdk1.7,scala plug-in scala-2.1.1.2-site.zip)1: Download Scala pluginHttp://download.scala-ide.org/sdk/helium/e38/scala211/stable/site 2: Unzip to LocalCopy all of the jar packages from the two files to the folder in the installation directory for Eclipse three: Restart Eclipse this will prompt you to have the plugin not enabled, click OK Four: Creat

Pattern matching using extractor: When an instance of a class is followed by parentheses using a list of 0 or more parameters, the compiler invokes the applied method on that instance. We can define both objects and classes. As mentioned above, the purpose of the Unapply method is to extract a particular value from what we are looking for. It operates in the opposite way as apply. An extract object that compares the Unapply method in a matching statement is automatically executed, as follows: Ob

Overview In short, implicit conversions are: When a Scala compiler does a type match, if the appropriate candidate is not found, implicit conversion provides another way to tell the compiler how to convert the current type to the expected type. The source of this article: http://blog.csdn.net/bluishglc/article/details/50866314 is strictly prohibited in any form of reprint, otherwise will entrust CSDN official maintenance rights and interests. Implici

how to rely on Scala's language features for high-force dependency injection What is dependency injection.Object is an abridged unit in the object-oriented world, and dependency injection groups the objects together. The simplest way to look at it is to inject the dependency into the object through a constructor or setter method.If we use the appropriate container, we can also extract the dependencies of each component of the system into the configuration file or configuration code, and inject

Implicit is a very important feature in Scala and has been thinking about it as much as Java before starting to learn Scala, but it's not as easy to see some of Scala's source code as it is, so I'm going to write a few articles to explain the features of Scala that are different from Java. Implicit, let's get started. In my opinion, what implicit do is also the m

"Statement" The content of this post is copy, the source is the stack overflow.It has several meanings in Scala and all related to its mathematical meaning as implication. In a value, it introduces a function literal, or lambda. e.g. the bit inside the curly braces inList(1,2,3).map { (x: Int) => x * 2 } In a type, with symbols on both sides of the arrow (e.g. a = t , (b) + t , (a,b,c) = + T , etc.) It's sugar for function, that's, A Funct

scala-02 function definition, Process control, exception handlingFirst, theScala function definition:( The package is imported by default when the Scala function is defined)(1)val: variable (constant) similar to final type in Java 1, basic format: val variable name: variable type = value 2, where variable types can be omitted and can be automatically identified3, variable cannot be assigned, modifyvar

Lesson 2nd: Scala's object-oriented mastery and spark source readingContents of this issue:1 Scala's class, object in real combat2 abstract classes and interfaces in Scala3 comprehensive case and spark source code analysisOne: Define ClassClass hiscala{private var name = "Spark"Def sayname () {println (name)}def getName = Name}In Scala, a variable is the same as a method in a class and can be assigned directly to a method.There is a big difference bet

Scala multi-inheritance, constructor execution order, AOP implementation Trait implementations of multiple inheritance: Scala interfaces can inherit specific classes, trait interfaces can implement multiple inheritance, and a class can inherit a particular class, which can be mixed in after inheritance, the implementation of an interface Multi-inheritance constructor execution order: The ex

First-class functionsScala's functions are the first-class functions (first-class function). Not only can you define and invoke functions, you can also write them as anonymous literals (literal) and pass them as values.The function literal is compiled into the class and instantiated at run time as a function value. What do you mean? The essence of a function is an instance of a class. a function is a collection of attributes, and any function value is an instance of a class that extends one of s

CharacteristicsThe Java interface in Scala is trait (feature). It's actually more powerful than the interface. Unlike interfaces, it can also define the implementation of properties and methods. Features in Scala are used to serve the modularity of a single-purpose functional module. Scala is designed to meet the functional requirements of various applications by

The name of a function language comes from the concept that the program behavior should be like a mathematical function; in other words, given a set of inputs, the function should always return the same output. This not only means that each function must return a value, but also means that from one call to the next call, the function must not have an intrinsic State in nature ). This kind of stateless concept (in the function/object field, it is always an object by default ), it is the main reas