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A Flock of Functions: Combinators, Lambda Calculus, & Church Encodings in JS

Home Page: https://glebec.github.io/lambda-talk

License: MIT License

JavaScript 100.00%

lambda-calculus church-encodings composition functional-programming mathematics theory-of-computation javascript combinatory-logic combinators currying

lambda-talk's Introduction

𝜆as.js, or A Flock of Functions

Combinators, Lambda Calculus, and Church Encodings in JavaScript

This repo contains notes and runnable examples of the lambda calculus as expressed through JavaScript.

Visit https://glebec.github.io/lambda-talk for a formatted version of the code.

The runnable JS file is in src/index.js. Execute the file is by cloning this repo and running npm start. Or, view the REPL here.

Presentation

This repo was created as an accompaniment to a lecture talk given at Fullstack Academy of Code on 2017-08-24. You can view videos of that talk (in two parts) below:

Part I

Part II

Slides

Click to view the original slide deck.

Update: the first part of the presentation has been slightly modified over time; the deck used for the 2019-10 Smartly.io DevTalks can be seen here.

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lambda-talk's Issues

Z combinator

Gabriel, I've followed your presentation. I'm now trying to take it further by implementing the z combinator. To make sure it works I'm trying to implement factorials using it. I can't find a clear demonstration which uses church numerals and doesn't cheat on the recursion. Could you please shed some light on this? Here is the exact code I have so far: https://github.com/willpiam/lambda-calculus/blob/master/index.js

Thank you for the insightful presentation and for your time.
William Doyle

In slides #307 through #311, the JavaScript function is labeled 'eq'. It should be 'gt'.

I am referring to the PDF version of the slide deck. The affected page numbers are 307-311, and 313.

The lambda function on these 6 slides are all correctly labeled as 'GT'. But the equivalent JS version of the function below has the label 'eq' on all the 6 slides.

Not a biggie, though. Thanks for the very well-presented talk. Thanks!

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