Extending JavaScript the easy way

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Extending JavaScript the easy way Sergi Mansilla, November 2012

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@sergimansilla

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JavaScript is popular

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It is ASM for the web

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CoffeeScript LispyScript JWacs FlapJax Elm Coco FBJS JS11 Roy Streamline JS TypeScript Objective J JS2 Jack Source: http://altjs.org

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Be JavaScript, my friend

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...but it is far from perfect

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No content

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Macros ultimate flexibility (ES6 won't have them, btw)

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Macros provide a way to extend syntax Syntax Syntax Macro

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Users can extend the language

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It helps evolving the language faster

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sweet.js Macros for JavaScript

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sweet.js Modeled after Scheme macros

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Sweet.js Syntax Syntax Macro JS + Macros JS Sweet.js

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Redefine 'function'

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Redefine 'function'

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Destructuring

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Destructuring

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Destructuring

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Destructuring

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Destructuring

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Destructuring

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Destructuring

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Nice ranges!

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case-style assignment

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case-style assignment

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Use cases Try proposed syntax before it makes into the language Create Micro-DSLs for your scenario Use ideas from other languages Make the new Script Implement basic types You get the idea

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Start using it now > npm install sweet.js > sjs -o output.js test_macros.sjs > node output.js Node.js Browser https://github.com/iammerrick/require-sweet

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Questions?

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Thanks! @sergimansilla github.com/sergi sergimansilla.com

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http://sweetjs.org/ https://github.com/mozilla/sweet.js http://jlongster.com/why-sweet.js-matters http://scriptogr.am/micmath/post/sweet-macros-in- javascripthttps://news.ycombinator.com/item?id=4560691 http://youtu.be/_ahvzDzKdB0 References