Intro to Ruby

Objectives
Identify data types, operators, and control flow patterns in JavaScript and utilize them in Ruby
Apply Ruby control flow to create command line applications

Framing for the Week

As we learn Ruby, it's important to revisit how we learned our first language and use that to organize the study of our new language. Learning our second programming language is a process of translating concepts, expressions, and patterns from our familiar language into our new language. Learning our first language involved more identification and comprehension of the knowledge required to implement our first programs. We should begin by organizing this knowledge to build a better understanding as we transition to Ruby.

Types of Knowledge

  • Declarative Knowledge > your "what is" knowledge, i.e. describing what something is
  • Imperative knowledge > your "how to" knowledge, i.e. describing how to do something

Parts of A Language

  • Primitives
  • Combinations
  • Abstractions

Discussion Questions

  • What is JavaScript? What does it look like?
  • What are some of the primitives in JavaScript?
    • Think data types, variable declarations, conditionals, functions, etc.
  • How did we use JavaScript to build things? How did we build up from the fundamentals of the language?
  • What could possibly be different in another language? How could we change the syntax, but keep the semantics?

Base Challenges

Use irb in your terminal for these challenges. Feel free to copy your solutions into a file in Sublime so you can reference them later.

Data Types

  1. Store your first_name in a variable and your last_name in another variable.

  2. Concatenate your first_name and last_name variables, and store the output in a new variable called full_name.

  3. Use .split to turn your full_name variable into an array.

Loops

  1. Print (puts) "Ruby is awesome!" 50 times. Implement this 3 different ways, using:

  2. Save any string to a variable, then create an empty hash called count (count = {}). Loop through the string, and count occurrences of each letter. Store the counts in your hash like this example:

    • For the string apple, your count hash would look like this: {a: 1, p: 2, l: 1, e: 1}.

  3. Write a program that gets user input from the terminal and puts it until the input is the word "quit" or "q".

    • Hint: Use gets.chomp instead of gets to remove trailing \n.

  4. Write a program that prints the "bottles of beer on the wall" song:

    5 bottles of beer on the wall,
5 bottles of beer!
Take one down and pass it around,
4 bottles of beer on the wall!
...
    • Use gets.chomp to ask the user how many verses they want to hear.
    • Make sure your song prints "1 bottle of beer".
    • When the song gets to "0 bottles of beer on the wall", it should print "No more bottles of beer on the wall" instead.

Iterators: Each

  1. Define an array of 4 phrases: "Hello, world", "OMG", "Ruby", and "Pair Programming". Use .each to iterate over the array and puts each phrase.

  2. Iterate over your array of phrases again, but this time, only puts the phrase if its length 5 letters or longer. Otherwise, print a message that the phrase is too short, and include the phrase's index in the message (Hint: Look up .each_with_index).

Iterators: Map

  1. Write a program that maps an array of numbers to double each number.

  2. Write a program that maps an array of words to the reverse of each word. (Hint: Look up .reverse)

Let's have an HTTParty!

  1. Install the httparty gem $ gem install httparty.

  2. Now require it in a new ruby script file, and use it to call an album search on the word "White" to the spotify API.

  3. Can you require both httparty and awesome_print to have the output look nice? (remember just require awesome_print and then use ap instead of p)

  4. In the same file, can you write a loop that returns an array of the album names from your search?

Stretch Challenges

  1. Create a simple temperature convertor. It should function like the example below:

    Type '1' to convert from Celsius to Fahrenheit or '2' to convert from Fahrenheit to Celsius
1
Enter Celsius temperature:
24
24 degrees Celsius is equal to 75.2 degrees Fahrenheit

  2. Create a simple calculator that first asks the user what method they would like to use (addition, subtraction, multiplication, or division), then asks the user for two numbers, printing the result of the method with the two numbers. Here is a sample prompt:

    What calculation would you like to do? (add, sub, mult, div)
add
What is the first number?
3
What is the second number?
6
The result is 9

Docs & Resources