Source is a family of sublanguages of

JavaScript JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior. Web browsers have ...

, developed for the textbook Structure and Interpretation of Computer Programs, JavaScript Edition (SICP JS). The JavaScript sublanguages Source §1, Source §2, Source §3 and Source §4 are designed to be just expressive enough to support all examples of the respective chapter of the textbook.

Purpose and design principle

During the development of SICP JS, starting in 2008, it became clear that purpose-designed sublanguages of JavaScript would contribute to the learning experience. Initially called "JediScript" and inspired by the book "JavaScript: The Good Parts" by Douglas Crockford, the Source sublanguages follow the chapters of SICP JS; each language Source §x is a sublanguage of the next language Source §(x+1). Following the minimalistic approach of SICP JS, implementations of Source are expected to remove any JavaScript language features that are not included in the language specification.

Features

Source §1 is a very small purely functional sublanguage of JavaScript, designed for Chapter 1 of SICP JS. Source §2 adds pairs and a list library, following the data structures theme of Chapter 2. Source §3 adds stateful constructs, and Source §4 adds support for meta-circular evaluation. Chapter 5 of SICP JS does not require language support beyond Source §4. All Source languages are properly tail recursive, as required by Chapter 1 of SICP and as specified by

ECMAScript ECMAScript (; ES) is a standard for scripting languages, including JavaScript, JScript, and ActionScript. It is best known as a JavaScript standard intended to ensure the interoperability of web pages across different web browsers. It is stan ...

2015.

Source Academy

Since the Safari browser is

-2015-compliant, including proper tail calls, it can serve as an implementation of all Source languages, provided that the SICP package is loaded. The Source Academy is a web-based programming environment that implements all Source languages, regardless of browser support for proper tail calls, and features various tools for the readers of SICP JS. The language implementation in the Source Academy, js-slang, is also available as a stand-alone environment based on Node.js.

References

External links

* {{Use dmy dates, date=August 2017 Programming languages Scripting languages Cross-platform free software Cross-platform software Dynamic programming languages Dynamically typed programming languages Free and open source interpreters Free computer libraries Software using the Apache license