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installing MIT Schema

The SICP page recommends MIT scheme,
so that is what we will use

to install it, on Apple OSX using Homebrew:

  brew tap x11
  brew cask install xquartz

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Checkout a new working branch

 git checkout -b <branchname>

Make Changes

 git add
 git commit -m "description of changes"

Sync with remote

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// primitive types
let isOk: boolean = true;
let greeting: string = "Hello";
let count: number = 5;
let fruits: string[] = ["banana", "apple"]; // Array<string>
let tuple: [string, number] = ["hi", 10]; // tuple[3] = 1 <- error

enum Fruits {
  banana = "BANANA",
  apple = "APPLE",

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npm install --save-dev @babel/core @babel/preset-env

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#!/usr/bin/env node

console.log('Hello world!')

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var f = x => x * 10
f(100) //=> 1000

var f = x => console.log(x * 10)
f(100) //=> 1000

(x => console.log(x * 10))(10) //=> 100

(10)(x => console.log(x*10)) // Error

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0x594A1057366D4Db941f90F0D8311e50CB64a9979

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import re
import string

frequency = {}
document_text = open('test.txt', 'r')
text_string = document_text.read().lower()
match_pattern = re.findall(r'\b[a-z]{3,15}\b', text_string)

for word in match_pattern:
    count = frequency.get(word,0)

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module HashConverter
  class << self
    def to_underscore hash
      convert hash, :underscore
    end
    def to_camel_case hash
      convert hash, :camelize, :lower
    end
    def convert obj, *method
      case obj

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::uuid generates a v4 random UUID (Universally Unique IDentifier).

p SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
p SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
p SecureRandom.uuid #=> "62936e70-1815-439b-bf89-8492855a7e6b"

The version 4 UUID is purely random (except the version). It doesn’t contain meaningful information such as MAC address, time, etc.