Why code in Node . js often get rejected by SoundCloud Phil Calado - - PowerPoint PPT Presentation

Why code in Node . js often get rejected by SoundCloud Phil Calçado - SoundCloud @pcalcado http :// philcalcado . com Tuesday, October 1, 13

2011: Phil zieht nach Berlin Tuesday, October 1, 13

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> 11 hours of audio uploaded every minute ~ 200 million users / month Tuesday, October 1, 13

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hiring @ SoundCloud http://bit.ly/15DToNK Tuesday, October 1, 13

Phone Code Review Interviews O fg er Tuesday, October 1, 13

Phone Code Review Interviews O fg er Tuesday, October 1, 13

challenge until late 2012 Tuesday, October 1, 13

you can choose any language . % of submissions ~2011-2012 40 30 20 10 0 Ruby Java JavaScript (Node.js) C Clojure Scala Tuesday, October 1, 13

you can choose any language . rejected before interview invited for inverview 40 30 20 10 0 Ruby Java JavaScript (Node.js) C Clojure Scala Tuesday, October 1, 13

new challenge Tuesday, October 1, 13

you can choose any language . % of submissions on the past ~1 year 30 22.5 15 7.5 0 Ruby Java JavaScript (Node.js) Go Clojure Scala Tuesday, October 1, 13

you can choose any language . % of submissions on the past ~1 year 30 22.5 15 7.5 0 Ruby Java JavaScript (Node.js) Go Clojure Scala Tuesday, October 1, 13

you can choose any language . rejected before interview invited for inverview 30 22.5 15 7.5 0 Ruby Java JavaScript (Node.js) Go Clojure Scala Tuesday, October 1, 13

you can choose any language . rejected before interview invited for inverview WTF? 30 22.5 15 7.5 0 Ruby Java JavaScript (Node.js) Go Clojure Scala Tuesday, October 1, 13

don’t get me wrong we are all hipsters http://bit.ly/J1aLNn Tuesday, October 1, 13

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Not OO, not Functional... Just (bad) Procedural code. Tuesday, October 1, 13

http://bit.ly/JiECRp Tuesday, October 1, 13

we don’t need this complicated stu fg . this is not java, you know . Tuesday, October 1, 13

so how do we structure our app? http://bit.ly/JiFSnq Tuesday, October 1, 13

what to use? ( decent ) procedures? Tuesday, October 1, 13

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what to use? objects? Tuesday, October 1, 13

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what to use? ... functions? Tuesday, October 1, 13

http://bit.ly/JFbZt8 Tuesday, October 1, 13

“SICP and some of the Sussman & Steele " Lambda the ..." papers made a big impression on me years before, although I did not understand their full meaning then . Remember, I was recruited to " do Scheme " [...] My interest in languages such as Self informed a subversive agenda [...]. Likewise with first - class functions, which were inspired by Scheme [...] ” http://bit.ly/JFbZt8 Tuesday, October 1, 13

http://bit.ly/JiEQYM Tuesday, October 1, 13

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going old school http://bit.ly/JiF7ef Tuesday, October 1, 13

e . g . passing functions around Tuesday, October 1, 13

we see a lot of this Tuesday, October 1, 13

1st, we extract what is common Tuesday, October 1, 13

then we refactor our functions Tuesday, October 1, 13

and we send them as arguments Tuesday, October 1, 13

e . g . closures not only for objects Tuesday, October 1, 13

we see a lot of this Tuesday, October 1, 13

we can keep writeComment as it is Tuesday, October 1, 13

and we add a function with two closures Tuesday, October 1, 13

and we add a function with two closures immutable Tuesday, October 1, 13

and we add a function with two closures immutable mutable Tuesday, October 1, 13

now we don’t need to pass in the kitchen sink Tuesday, October 1, 13

e . g . functions all the way down Tuesday, October 1, 13

we see a lot of this Tuesday, October 1, 13

first we extract common protocol Tuesday, October 1, 13

then we clean up our functions Tuesday, October 1, 13

then we use them . Tuesday, October 1, 13

then we use them . redundant? Tuesday, October 1, 13

http://bit.ly/JiETnd Tuesday, October 1, 13

our “framework” : 1 - Extract protocol in “combinators” 2 - Keep mutable state in closures Tuesday, October 1, 13

no scary monads required Tuesday, October 1, 13

there is plenty to learn from Tuesday, October 1, 13

in the javascript community too Tuesday, October 1, 13

phil calçado http://philcalcado.com @pcalcado www.soundcloud.com Tuesday, October 1, 13

How to Design Programs - http://bit.ly/K0BfrL Structure and Interpretation of Computer Programs - http://bit.ly/K0BjYm The Art of the Metaobject Protocol http://amzn.to/K0BqU1 Purely Functional Data Structures http://amzn.to/JFn4KG Let Over Lambda - http://amzn.to/IMMkNO An Introduction to Lambda Calculi for Computer Scientists - http://amzn.to/IX8d1B All drawings are available as t-shirts from the awesome Diesel Sweeties - http://dieselsweeties.com/ Tuesday, October 1, 13