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secrets/

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Using graphviz to visualize abstract syntax trees

• Take the above ast.dot file
• Paste it into http://www.webgraphviz.com/
• It will generate a diagram like this:

• After you've written your first lexer and parser, write a function which walks the AST and "compiles" it into graphviz notation like the above

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#!/usr/bin/env node

var assert = require('assert');

// Each lexed token is a array of three integers:
// 1. the "token type": an index into the list of token patterns.
// 2. the index into the input string marking the start of this token.
// 3. the length of the token.

// The list of "token types" which our lexer understands:

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Robot arduino sketch

Some motor-control code for our robot kit.

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Writing eval() for simple math expressions

Rather than starting with lexing and parsing, this week we just assume we have those bits already working, so that we can jump straight to eval().

video:

recording of the meeting

diagrams:

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Stacked-PR workflow

Some notes about how I work with stacked branches (a.k.a. dependent PR's).

Kindof a pain but it works. This could probably be automated with some clever scripting against github's API.

Creating the first PR

Create your first PR as per normal:

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Navigating Youbora v5 / v6 confusion (iOS)

Youbora went through a significant refactor as they transitioned from v5 to v6 of their iOS video playback metrics collecting plugins.

While this change has improved some shortcomings in the v5 design, it has unfortunately been the source of some confusion, as their dev infra and resources seem to have bifurcated across this change:

• The v5 repos live on github while v6 live on bitbucket.

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mathterp

This is a series of problems / challenges around evaluating simple math expressions.

Problem A

Write a program which can evaluate infix addition operations of non-negative integers.

Example inputs:

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import UIKit
import PlaygroundSupport


// FeatureFlags vs. "BetaFlags".  BetaFlags are automatically false for AppStore builds, which provides
// an extra level of safety against accidentally shipping a build which has beta features enabled.


struct FeatureFlags {
    // Set to false to disable support for fancy doors.

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{
    "Min"     : ["William", "Jayden", "Omar"],
    "William" : ["Min", "Noam"],
    "Jayden"  : ["Min", "Amelia", "Ren", "Noam"],
    "Ren"     : ["Jayden", "Omar"],
    "Amelia"  : ["Jayden", "Adam", "Miguel"],
    "Adam"    : ["Amelia", "Miguel"],
    "Miguel"  : ["Amelia", "Adam"],
    "Noam"    : ["Jayden", "William"],
    "Omar"    : ["Ren", "Min"]