DOCSLIB.ORG

Scala Tutorial

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Scala Tutorial Scala Tutorial SCALA TUTORIAL Simply Easy Learning by tutorialspoint.com tutorialspoint.com i ABOUT THE TUTORIAL Scala Tutorial Scala is a modern multi-paradigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. Scala has been created by Martin Odersky and he released the first version in 2003. Scala smoothly integrates features of object-oriented and functional languages. This tutorial gives a great understanding on Scala. Audience This tutorial has been prepared for the beginners to help them understand programming Language Scala in simple and easy steps. After completing this tutorial, you will find yourself at a moderate level of expertise in using Scala from where you can take yourself to next levels. Prerequisites Scala Programming is based on Java, so if you are aware of Java syntax, then it's pretty easy to learn Scala. Further if you do not have expertise in Java but you know any other programming language like C, C++ or Python, then it will also help in grasping Scala concepts very quickly. Copyright & Disclaimer Notice All the content and graphics on this tutorial are the property of tutorialspoint.com. Any content from tutorialspoint.com or this tutorial may not be redistributed or reproduced in any way, shape, or form without the written permission of tutorialspoint.com. Failure to do so is a violation of copyright laws. This tutorial may contain inaccuracies or errors and tutorialspoint provides no guarantee regarding the accuracy of the site or its contents including this tutorial. If you discover that the tutorialspoint.com site or this tutorial content contains some errors, please contact us at [email protected] TUTORIALS POINT Simply Easy Learning Table of Content Scala Tutorial ........................................................................... 2 Audience .................................................................................. 2 Prerequisites ............................................................................ 2 Copyright & Disclaimer Notice .................................................. 2 Scala Overview ........................................................................ 8 Scala is object-oriented: ............................................................................ 8 Scala is functional: ..................................................................................... 8 Scala is statically typed: ............................................................................ 8 Scala runs on the JVM: ............................................................................. 8 Scala can Execute Java Code: .................................................................. 9 Scala vs Java: ........................................................................................... 9 Scala Web Frameworks: ........................................................................... 9 Scala Environment Setup ....................................................... 10 Installing Scala on Windows: ................................................................... 10 STEP (1): JAVA SETUP: ......................................................................... 10 STEP (2): SCALA SETUP: ..................................................................... 10 Installing Scala on Mac OS X and Linux .................................................. 11 STEP (1): JAVA SETUP: ........................................................................ 11 STEP (2): SCALA SETUP: ..................................................................... 11 Scala Basic Syntax ................................................................ 13 First Scala Program: ................................................................................ 13 INTERACTIVE MODE PROGRAMMING: ............................................... 13 SCRIPT MODE PROGRAMMING: .......................................................... 13 Basic Syntax: ........................................................................................... 14 Scala Identifiers: ...................................................................................... 15 ALPHANUMERIC IDENTIFIERS ............................................................. 15 OPERATOR IDENTIFIERS ..................................................................... 15 MIXED IDENTIFIERS .............................................................................. 15 LITERAL IDENTIFIERS ........................................................................... 15 Scala Keywords: ...................................................................................... 15 Comments in Scala ................................................................................. 16 Blank Lines and Whitespace: .................................................................. 16 Newline Characters: ................................................................................ 16 Scala Packages: ...................................................................................... 16 Scala Data Types ................................................................... 18 Scala Basic Literals: ................................................................................ 18 INTEGER LITERALS .............................................................................. 19 TUTORIALS POINT Simply Easy Learning FLOATING POINT LITERALS ................................................................ 19 BOOLEAN LITERALS............................................................................. 19 SYMBOL LITERALS ............................................................................... 19 CHARACTER LITERALS........................................................................ 19 STRING LITERALS ................................................................................ 19 MULTI-LINE STRINGS ........................................................................... 19 THE NULL VALUE .................................................................................. 20 ESCAPE SEQUENCES: ......................................................................... 20 Scala Variables ...................................................................... 21 Variable Declaration ................................................................................ 21 Variable Data Types: ............................................................................... 21 Variable Type Inference: ......................................................................... 22 Multiple assignments: .............................................................................. 22 Variable Types: ........................................................................................ 22 FIELDS: ................................................................................................... 22 METHOD PARAMETERS: ...................................................................... 22 LOCAL VARIABLES: ............................................................................... 22 Scala Access Modifiers .......................................................... 23 Private members: .................................................................................... 23 Protected members: ................................................................................ 23 Public members: ...................................................................................... 24 Scope of protection: ................................................................................. 24 Scala Operators ..................................................................... 25 Arithmetic Operators: ............................................................................... 25 Example: ................................................................................................. 25 Relational Operators: ............................................................................... 26 Example: ................................................................................................. 27 Logical Operators: ................................................................................... 27 Example: ................................................................................................. 27 Bitwise Operators: ................................................................................... 28 Example .................................................................................................. 29 Assignment Operators: ............................................................................ 30 Example: ................................................................................................. 30 Operator Precedence in Scala: ................................................................ 31 Scala IF…ELSE Statements .................................................. 33 The if Statement: ..................................................................................... 33 SYNTAX: ................................................................................................. 33 EXAMPLE:............................................................................................... 34 The if...else Statement: ............................................................................ 34 TUTORIALS POINT Simply Easy Learning SYNTAX: ................................................................................................. 34 EXAMPLE: .............................................................................................
Load more

Recommended publications
  • Armadillo C++ Library
    Armadillo: a template-based C++ library for linear algebra Conrad Sanderson and Ryan Curtin Abstract The C++ language is often used for implementing functionality that is performance and/or resource sensitive. While the standard C++ library provides many useful algorithms (such as sorting), in its current form it does not provide direct handling of linear algebra (matrix maths). Armadillo is an open source linear algebra library for the C++ language, aiming towards a good balance between speed and ease of use. Its high-level application programming interface (function syntax) is deliberately similar to the widely used Matlab and Octave languages [4], so that mathematical operations can be expressed in a familiar and natural manner. The library is useful for algorithm development directly in C++, or relatively quick conversion of research code into production environments. Armadillo provides efficient objects for vectors, matrices and cubes (third order tensors), as well as over 200 associated functions for manipulating data stored in the objects. Integer, floating point and complex numbers are supported, as well as dense and sparse storage formats. Various matrix factorisations are provided through integration with LAPACK [3], or one of its high performance drop-in replacements such as Intel MKL [6] or OpenBLAS [9]. It is also possible to use Armadillo in conjunction with NVBLAS to obtain GPU-accelerated matrix multiplication [7]. Armadillo is used as a base for other open source projects, such as MLPACK, a C++ library for machine learning and pattern recognition [2], and RcppArmadillo, a bridge between the R language and C++ in order to speed up computations [5].
    [Show full text]
  • Higher-Order Functions 15-150: Principles of Functional Programming – Lecture 13
    Higher-order Functions 15-150: Principles of Functional Programming { Lecture 13 Giselle Reis By now you might feel like you have a pretty good idea of what is going on in functional program- ming, but in reality we have used only a fragment of the language. In this lecture we see what more we can do and what gives the name functional to this paradigm. Let's take a step back and look at ML's typing system: we have basic types (such as int, string, etc.), tuples of types (t*t' ) and functions of a type to a type (t ->t' ). In a grammar style (where α is a basic type): τ ::= α j τ ∗ τ j τ ! τ What types allowed by this grammar have we not used so far? Well, we could, for instance, have a function below a tuple. Or even a function within a function, couldn't we? The following are completely valid types: int*(int -> int) int ->(int -> int) (int -> int) -> int The first one is a pair in which the first element is an integer and the second one is a function from integers to integers. The second one is a function from integers to functions (which have type int -> int). The third type is a function from functions to integers. The two last types are examples of higher-order functions1, i.e., a function which: • receives a function as a parameter; or • returns a function. Functions can be used like any other value. They are first-class citizens. Maybe this seems strange at first, but I am sure you have used higher-order functions before without noticing it.
    [Show full text]
  • Java (Programming Langua a (Programming Language)
    Java (programming language) From Wikipedia, the free encyclopedialopedia "Java language" redirects here. For the natural language from the Indonesian island of Java, see Javanese language. Not to be confused with JavaScript. Java multi-paradigm: object-oriented, structured, imperative, Paradigm(s) functional, generic, reflective, concurrent James Gosling and Designed by Sun Microsystems Developer Oracle Corporation Appeared in 1995[1] Java Standard Edition 8 Update Stable release 5 (1.8.0_5) / April 15, 2014; 2 months ago Static, strong, safe, nominative, Typing discipline manifest Major OpenJDK, many others implementations Dialects Generic Java, Pizza Ada 83, C++, C#,[2] Eiffel,[3] Generic Java, Mesa,[4] Modula- Influenced by 3,[5] Oberon,[6] Objective-C,[7] UCSD Pascal,[8][9] Smalltalk Ada 2005, BeanShell, C#, Clojure, D, ECMAScript, Influenced Groovy, J#, JavaScript, Kotlin, PHP, Python, Scala, Seed7, Vala Implementation C and C++ language OS Cross-platform (multi-platform) GNU General Public License, License Java CommuniCommunity Process Filename .java , .class, .jar extension(s) Website For Java Developers Java Programming at Wikibooks Java is a computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few impimplementation dependencies as possible.ble. It is intended to let application developers "write once, run ananywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to rurun on another. Java applications ns are typically compiled to bytecode (class file) that can run on anany Java virtual machine (JVM)) regardless of computer architecture. Java is, as of 2014, one of tthe most popular programming ng languages in use, particularly for client-server web applications, witwith a reported 9 million developers.[10][11] Java was originallyy developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems'Micros Java platform.
    [Show full text]
  • Not-Dead-Yet--Java-On-Desktop.Pdf
    NOT DEAD YET Java on Desktop About me… Gerrit Grunwald 2012… The desktop is dead… …the future of applications… …is the Web ! 8 years later… My application folder… My applications folder (future) My applications folder (reality) ??? Seems desktop is not dead ! But what about Java ? Available Toolkits AWT Abstract Window Toolkit Abstract Window Toolkit Since 1995 Cross Platform Platform dependent Bound to native controls Interface to native controls SWT Standard Window Toolkit Standard Window Toolkit Based on IBM Smalltalk from 1993 Cross Platform Platform dependent Wrapper around native controls Java Swing Successor to AWT Java Swing Since Java 1.2 (1998) Cross Platform Platform independent Introduced Look and Feels Emulates the appearance of native controls Java FX Script Intended successor to Swing Java FX Script Since Java 1.6 (2008) Cross Platform Platform independent No Java Syntax Declarative way to describe UI's (based on F3 from Chris Oliver) Java FX Successor to Swing Java FX Since Java 7 (2011) Cross Platform Platform independent Port from JavaFX Script to Java Not part of the Java SE distribution since Java 11 Most of these are still in use… Is Java FX dead ? Is Java FX dead ? Open Sourced as OpenJFX (openjfx.io) Driven by the community Can run on mobile using Gluon technology (gluonhq.com) Can run on web using JPro technology (jpro.one) Actively developed and is getting new features too Where does Java on Desktop suck ? Lack of 3rd party controls Swing had great support over years, JavaFX lacks behind Missing features… e.g.
    [Show full text]
  • Typescript Language Specification
    TypeScript Language Specification Version 1.8 January, 2016 Microsoft is making this Specification available under the Open Web Foundation Final Specification Agreement Version 1.0 ("OWF 1.0") as of October 1, 2012. The OWF 1.0 is available at http://www.openwebfoundation.org/legal/the-owf-1-0-agreements/owfa-1-0. TypeScript is a trademark of Microsoft Corporation. Table of Contents 1 Introduction ................................................................................................................................................................................... 1 1.1 Ambient Declarations ..................................................................................................................................................... 3 1.2 Function Types .................................................................................................................................................................. 3 1.3 Object Types ...................................................................................................................................................................... 4 1.4 Structural Subtyping ....................................................................................................................................................... 6 1.5 Contextual Typing ............................................................................................................................................................ 7 1.6 Classes .................................................................................................................................................................................
    [Show full text]
  • Smalltalk Smalltalk
    3/8/2008 CSE 3302 Programming Languages Smalltalk Everyygthing is obj ect. Obj ects communicate by messages. Chengkai Li Spring 2008 Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 1 CSE3302 Programming Languages, UT-Arlington 2 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Object Hierarchy Object UndefinedObject Boolean Magnitude Collection No Data Type. True False Set … There is only Class. Char Number … Fraction Integer Float Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 3 CSE3302 Programming Languages, UT-Arlington 4 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Syntax • Smalltalk is really “small” – Only 6 keywords (pseudo variables) – Class, object, variable, method names are self explanatory Sma llta lk Syn tax is Simp le. – Only syntax for calling method (messages) and defining method. • No syntax for control structure • No syntax for creating class Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 5 CSE3302 Programming Languages, UT-Arlington 6 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 1 3/8/2008 Expressions Literals • Literals • Number: 3 3.5 • Character: $a • Pseudo Variables • String: ‘ ’ (‘Hel’,’lo!’ and ‘Hello!’ are two objects) • Symbol: # (#foo and #foo are the same object) • Variables • Compile-time (literal) array: #(1 $a 1+2) • Assignments • Run-time (dynamic) array: {1. $a. 1+2} • Comment: “This is a comment.” • Blocks • Messages Lecture 14 – Smalltalk, Spring Lecture 14 – Smalltalk, Spring CSE3302 Programming Languages, UT-Arlington 7 CSE3302 Programming Languages, UT-Arlington 8 2008 ©Chengkai Li, 2008 2008 ©Chengkai Li, 2008 Pseudo Variables Variables • Instance variables.
    [Show full text]
  • 1 Aliasing and Immutability
    Vocabulary: Accessors & Mutators Computer Science and Engineering The Ohio State University Accessor: A method that reads, but never changes, the Aliasing and Immutability (abstract) state of an object Computer Science and Engineering College of Engineering The Ohio State University Concrete representation may change, so long as change is not visible to client eg Lazy initialization Examples: getter methods, toString Lecture 8 Formally: restores “this” Mutator method: A method that may change the (abstract) state of an object Examples: setter methods Formally: updates “this” Constructors not considered mutators A Fixed Epoch Interface A Broken Time Period Class Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University // Interface cover story goes here public class Period implements FixedEpoch { // Mathematical modeling … private Date start; // constructor private Date end; // requires start date < end date // initializes start and end dates // operations have specifications based on the model public Period(Date start, Date end) { // exercises … this.start = start; this.e nd = e nd; public interface FixedEpoch { } public Date getStart(); public Date getEnd(); } public Date getStart() { return start; } public Date getEnd() { return end; } } Problem: Aliasing A Better Period Class Computer Science and Engineering The Ohio State University Computer Science and Engineering The Ohio State University Assignment in constructor creates an alias public class Period
    [Show full text]
  • Python Functions
    PPYYTTHHOONN FFUUNNCCTTIIOONNSS http://www.tutorialspoint.com/python/python_functions.htm Copyright © tutorialspoint.com A function is a block of organized, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing. As you already know, Python gives you many built-in functions like print, etc. but you can also create your own functions. These functions are called user-defined functions. Defining a Function You can define functions to provide the required functionality. Here are simple rules to define a function in Python. Function blocks begin with the keyword def followed by the function name and parentheses ( ). Any input parameters or arguments should be placed within these parentheses. You can also define parameters inside these parentheses. The first statement of a function can be an optional statement - the documentation string of the function or docstring. The code block within every function starts with a colon : and is indented. The statement return [expression] exits a function, optionally passing back an expression to the caller. A return statement with no arguments is the same as return None. Syntax def functionname( parameters ): "function_docstring" function_suite return [expression] By default, parameters have a positional behavior and you need to inform them in the same order that they were defined. Example The following function takes a string as input parameter and prints it on standard screen. def printme( str ): "This prints a passed string into this function" print str return Calling a Function Defining a function only gives it a name, specifies the parameters that are to be included in the function and structures the blocks of code.
    [Show full text]
  • Functional Programming Inside OOP?
    Functional Programming inside OOP? It’s possible with Python >>>whoami() Carlos Villavicencio ● Ecuadorian θ ● Currently: Python & TypeScript ● Community leader ● Martial arts: 剣道、居合道 ● Nature photography enthusiast po5i Cayambe Volcano, 2021. >>>why_functional_programming ● Easier and efficient ● Divide and conquer ● Ease debugging ● Makes code simpler and readable ● Also easier to test >>>history() ● Functions were first-class objects from design. ● Users wanted more functional solutions. ● 1994: map, filter, reduce and lambdas were included. ● In Python 2.2, lambdas have access to the outer scope. “Not having the choice streamlines the thought process.” - Guido van Rossum. The fate of reduce() in Python 3000 https://python-history.blogspot.com/2009/04/origins-of-pythons-functional-features.html >>>has_django_fp() https://github.com/django/django/blob/46786b4193e04d398532bbfc3dcf63c03c1793cb/django/forms/formsets.py#L201-L213 https://github.com/django/django/blob/ca9872905559026af82000e46cde6f7dedc897b6/django/forms/formsets.py#L316-L328 Immutability An immutable object is an object whose state cannot be modified after it is created. Booleans, strings, and integers are immutable objects. List and dictionaries are mutable objects. Thread safety >>>immutability def update_list(value: list) -> None: def update_number(value: int) -> None: value += [10] value += 10 >>> foo = [1, 2, 3] >>> foo = 10 >>> id(foo) >>> update_number(foo) 4479599424 >>> foo >>> update_list(foo) 10 >>> foo 樂 [1, 2, 3, 10] >>> id(foo) 4479599424 >>>immutability def update_number(value: int) -> None: print(value, id(value)) value += 10 print(value, id(value)) >>> foo = 10 >>> update_number(foo) 10 4478220880 ڃ 4478221200 20 >>> foo 10 https://medium.com/@meghamohan/mutable-and-immutable-side-of-python-c2145cf72747 Decorators They are functions which modify the functionality of other functions. Higher order functions.
    [Show full text]
  • Php Foreach Array Example
    Php Foreach Array Example Positivism Sonnie always besought his dimeters if Esme is fruticose or touch-types incompletely. Sometimes anything.plenipotentiary Zane Gordieemits unobtrusively alchemise her while foreman untrained slower, Harlan but bubbliest presages Rodge obsoletely strides or pippingriotously masterfully. or recapitalizes You can have explored deep are using array_map prevents you forgot, and will keep multiple. How we have an associative array is a different values are times has a numeric array and arrays can be obtained by working along. This url into two variables are such type. PHP 4 introduced foreach construct it works only on arrays. Let's understand this with the help bear the porter example. The running one uses it. PHP foreach Manual. Sample PHP Code PHP For Loops Foreach While ago Do. Arrayvalue is your temporary variable that holds the current total item values block of code is the its of code that operates on already array values Example 1. Usually depending on my favourite site for passing it on how if statement. PHP foreach loops FreeKB. Start from any one statement is that, instead of items in an example of each elements with examples to get an array. PHP foreach within foreach repeat data flow not escaping loops. Of iteration helps you can access or public route on here? PHP foreach Loop GeeksforGeeks. Foreach Semantic portal learn smart. Nested for loops One for brother can be no inside another for purpose and force can generate different scripts using nested loops Here is an intelligence for. Here there is used in a block on array index or break statement or associative array by using a multidimensional array an.
    [Show full text]
  • Cmsc 132: Object-Oriented Programming Ii
    © Department of Computer Science UMD CMSC 132: OBJECT-ORIENTED PROGRAMMING II Iterator, Marker, Observer Design Patterns Department of Computer Science University of Maryland, College Park © Department of Computer Science UMD Design Patterns • Descriptions of reusable solutions to common software design problems (e.g, Iterator pattern) • Captures the experience of experts • Goals • Solve common programming challenges • Improve reliability of solution • Aid rapid software development • Useful for real-world applications • Design patterns are like recipes – generic solutions to expected situations • Design patterns are language independent • Recognizing when and where to use design patterns requires familiarity & experience • Design pattern libraries serve as a glossary of idioms for understanding common, but complex solutions • Design patterns are used throughout the Java Class Libraries © Department of Computer Science UMD Iterator Pattern • Definition • Move through collection of objects without knowing its internal representation • Where to use & benefits • Use a standard interface to represent data objects • Uses standard iterator built in each standard collection, like List • Need to distinguish variations in the traversal of an aggregate • Example • Iterator for collection • Original • Examine elements of collection directly • Using pattern • Collection provides Iterator class for examining elements in collection © Department of Computer Science UMD Iterator Example public interface Iterator<V> { bool hasNext(); V next(); void remove();
    [Show full text]
  • Iterators in C++ C 2016 All Rights Reserved
    Software Design Lecture Notes Prof. Stewart Weiss Iterators in C++ c 2016 All rights reserved. Iterators in C++ 1 Introduction When a program needs to visit all of the elements of a vector named myvec starting with the rst and ending with the last, you could use an iterative loop such as the following: for ( int i = 0; i < myvec.size(); i++ ) // the visit, i.e., do something with myvec[i] This code works and is a perfectly ne solution. This same type of iterative loop can visit each character in a C++ string. But what if you need code that visits all elements of a C++ list object? Is there a way to use an iterative loop to do this? To be clear, an iterative loop is one that has the form for var = start value; var compared to end value; update var; {do something with node at specic index} In other words, an iterative loop is a counting loop, as opposed to one that tests an arbitrary condition, like a while loop. The short answer to the question is that, in C++, without iterators, you cannot do this. Iterators make it possible to iterate through arbitrary containers. This set of notes answers the question, What is an iterator, and how do you use it? Iterators are a generalization of pointers in C++ and have similar semantics. They allow a program to navigate through dierent types of containers in a uniform manner. Just as pointers can be used to traverse a linked list or a binary tree, and subscripts can be used to traverse the elements of a vector, iterators can be used to sequence through the elements of any standard C++ container class.
    [Show full text]