Snap''!'' (formerly Build Your Own Blocks) is a free, block-based

educational Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty. Vari ...

graphical programming language and online community allowing students to explore, create, and remix interactive animations, games, stories, and more, while learning about mathematical and computational ideas. While inspired by Scratch, Snap''!'' has many advanced features. The Snap''!'' editor, and programs created in it, are

web application A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serve ...

s that run in the browser (like Scratch 3) without requiring installation.

User interface

In Snap''!'', the screen is organized in three resizable columns containing five regions: the block group selector (top of left column), the blocks palette (left column), the main area (middle column), and the stage area (top of right column) with the sprite selector (also called the sprite corral) showing sprite thumbnails below it. In the interactively resizable stage area are shown the graphical results of the scripts running in the script area and/or interactively double-clicked individual blocks in any palette. Individual blocks can be dragged from the palette onto the scripts area to be associated with the selected sprite. Snap''!s blocks are divided into eight groups: Motion, Looks, Sound, Pen, Control, Sensing, Operators, and Variables. The layout of these groups in the block group selector is shown in the table below. The central area can show scripts, costumes, or sounds associated with the selected sprite. What that area shows depends on the selected tab.

Features

The most important features that Snap''!'' offers, but Scratch does not, include: * expressions using anonymous functions, represented by a block inside a gray ring, having one or more empty slot(s)/argument(s) that are filled by a "higher order function" (the one that is calling the anonymous one). (Their computer-science theoretical basis is

First class function In computer science, a programming language is said to have first-class functions if it treats functions as first-class citizens. This means the language supports passing functions as arguments to other functions, returning them as the values from ...

s, which in turn have

Lambda calculus Lambda calculus (also written as ''λ''-calculus) is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution. It is a universal model of computation t ...

as their even more abstract, mathematical, foundation), * lists that are first class (including ''lists of lists/arrays''), * ''First class'' sprites (in other words prototype-oriented instance-based classless object programming), * "Hyperblocks": functions whose natural domain is scalars (text or numbers), extended to accept lists as inputs and apply the underlying function to the scalars in the list or a sublist, * nestable sprites, * codification of Snap''!'' programs to text languages such as Python, JavaScript, C, etc. *

metaprogramming Metaprogramming is a programming technique in which computer programs have the ability to treat other programs as their data. It means that a program can be designed to read, generate, analyze or transform other programs, and even modify itself ...

, reflection, and macros.

Mascot

Alonzo, the mascot of Snap''!'', bears the name of

Alonzo Church Alonzo Church (June 14, 1903 – August 11, 1995) was an American mathematician, computer scientist, logician, philosopher, professor and editor who made major contributions to mathematical logic and the foundations of theoretical computer scie ...

, the inventor of a model of computation in which a universal function, represented by lambda, can create any function behavior by calling it on itself in various combinations. The mascot is a modified version of Gobo from Scratch. Because Alonzo Church's work is called

lambda calculus Lambda calculus (also written as ''λ''-calculus) is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution. It is a universal model of computation t ...

, the mascot's hair is shaped as the Greek letter

lambda Lambda (}, ''lám(b)da'') is the 11th letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoenician Lamed . Lambda gave ris ...

Special-purpose blocks (libraries)

Extended sets of blocks can be found in Snap''!'' libraries, such as the 'streams' library that enables one to make the complete, infinite

Fibonacci sequence In mathematics, the Fibonacci numbers, commonly denoted , form a sequence, the Fibonacci sequence, in which each number is the sum of the two preceding ones. The sequence commonly starts from 0 and 1, although some authors start the sequence from ...

, for example, using the special blocks ('stream', 'show stream', 'tail of stream', and 'map ( ) over stream' block) from the library. Many other libraries are available, such as the 'list utilities' library, the 'words, sentences' library, the 'iterations' library, the 'animation' library, the 'frequency distribution' library, the 'audio computation' library, the 'bar charts' library, the 'world map' library, the 'colors and crayons' library, the 'strings and multi-line input' library, the 'parallelization' library, etc. for other special purposes.

History

The web-based Snap''!'' and older desktop-base
BYOB
have been both developed by Jens Mönig for

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

and

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

with design ideas and documentation provided by

Brian Harvey Brian Lee Harvey (born 8 August 1974) is a British singer from London. He was the lead singer of pop group East 17. The later incarnation of the band, E-17, had two top 20 singles on the UK Singles Chart between 1998 and 1999, with the album ' ...

from

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

and have been used to teach "The Beauty and Joy of Computing" introductory course in

computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...

(CS) for non-CS-major students. Jens was a member of th
Scratch Team
before creating ''Snap!''. BYOB is still available for downloading.

License

The source code of Snap''!'' is

Affero General Public License The Affero General Public License (Affero GPL and informally Affero License) is a free software license. The first version of the Affero General Public License (AGPLv1), was published by Affero, Inc. in March 2002, and based on the GNU General Pu ...

(AGPL) licensed and is hosted on

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, co ...

. The earlier, desktop-based 3.x version's code is available under a license that allows modification for only non-commercial uses and can be downloaded from the UC Berkeley website or CNET's Download.com and TechTracker download page.

Platforms

Snap''!'' is implemented in JavaScript using an

HTML5 HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and final major HTML version that is a World Wide Web Consortium (W3C) recommendation. The current specification is known as the HT ...

Canvas application programming interface (API), and because of that it runs on the major web-browsers on

, iOS,

and

devices.

Recognition

Snap''!'' has been recognized by the Logo Foundation, and reviewed in an online magazine for programmers. As of December 2014, 100 New York City (NYC) high schools will introduce University of California, Berkeley's “Beauty and Joy of Computing” as a new AP Computer Science Principles course starting in 2015, using Snap''!''. Jens and Brian received the National Technology Leadership Summit (NTLS) 2020 Educational Leadership Award for lifetime achievement based in part on Snap''!''.

Notes

References

External links

* {{DEFAULTSORT:Snap! (Programming Language) American children's websites Educational programming languages Free educational software Pedagogic integrated development environments Smalltalk programming language family Video game development software Software developer communities Visual programming languages