Ruby is an object-oriented scripting language with features like mixins, metaprogramming, and dynamic typing. It allows defining functions and methods that can take blocks or lambdas as arguments. Arrays, hashes, and ranges provide ways to iterate over collections. Strings support interpolation and methods like split. Classes define methods that can access attributes. The JSON library extends core types like Hash to add methods like to_json for serialization.

1. Ruby Language Overview

2. Features
●Object-Oriented
●Mixins
●Very Dynamic
●Metaprogramming

3. Alright, simple enough
a = "Hello, Ruby"
puts a
=> "Hello, Ruby"

4. Functions
def plus(a, b)
a+b
end
plus(1,2)
=> 3

5. Method calls without parentheses
def plus(a, b)
a+b
end
plus 1, 2 # WAT
=> 3

6. Arrays, hashes, ranges
# List of string, float, string, int and hash
array = ["Hello", 3.14, "ruby", 1, {hello: "hi"}]
for i in array
puts i
end
>> Hello
>> 3.14
>> ruby
>> 1
>> {:hello=>"hi"}

7. Arrays, hashes, ranges
for i in 1..10
puts i
end
for i in 'a'..'z'
puts i
end
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x,
y, z

8. Arrays, hashes, ranges
# split(“ “)
puts %w(I still love you Kotlin)
"I",
"still",
"love",
"you",
"Kotlin"

9. String interpolation
a = 1
b = 4
puts "The number #{a} is less than #{b}"
puts "%0.5d" % 5
>> "The number 1 is less than 4"
>> "00005"

10. Blocks (lambdas)
5.times do |x|
puts "x inside the block: #{x}"
end
('a'..'z').each {|i| puts i}
>> x inside the block: 0
>> x inside the block: 1
>> x inside the block: 2
>> x inside the block: 3
>> x inside the block: 4
a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x,
y, z

11. Functional programming
array.length.downto(1).map {|n| "I said #{n}"}

12. Classes and methods
class Sample < Base
def hello
puts "Hello Ruby!"
@field = "Field"
local = "Local variable"
end
end

13. Bonus
reponse = {
title: "Harry Potter and the Gradle Build",
description: "Book by J.K. Rowling",
attrs: {
pages: 192,
worth_reading: true
},
reviews: [ "Awesome!", "Great" ]
}
puts reponse.to_json
NoMethodError: undefined method `to_json' for #<Hash:0x007fcdb18f84b0>
from (irb):19
from /usr/bin/irb:12:in `<main>'

14. Bonus (Extension functions)
require "json" #
...
puts reponse.to_json
{
"title": "Harry Potter and the Gradle Build",
"description": "Book by J.K. Rowling",
"attrs": {
"pages": 192,
"worth_reading": true
},
"reviews": [
"Awesome!",
"Great"
]
}