spoiling the youth with ruby (euruko 2010)

Spoiling The Youth With RubyEURUKO 2010

Karel Minařík

Spoiling the Youth With Ruby

Karel Minařík

→ Independent web designer and developer („Have Ruby — Will Travel“)

→ Ruby, Rails, Git and CouchDB propagandista in .cz

→ Previously: Flash Developer; Art Director; Information Architect;… (see LinkedIn)

→ @karmiq at Twitter

→ karmi.cz

http://karmi.cz

http://karmi.cz


I have spent couple of last years introducing spoiling humanities students to with the basics of PR0GR4MM1NG.(As a PhD student)

I’d like to share why and how I did it.

And what I myself have learned in the process.


I don’t know if I’m right.


But a bunch of n00bz was able to:

‣ Do simple quantitative text analysis (count number of pages, etc)

‣ Follow the development of a simple Wiki web application and write code on their own

‣ Understand what $ curl ‐i ‐v http://example.com does‣ And were quite enthusiastic about it

5 in 10 have „some experience“ with HTML

1 in 10 have „at last minimal experience“ with programming (PHP, C, …)

ΓΝΩΘΙ ΣΕΑΥΤΟN

Socrates


Socrates is guilty of spoling the youth (ἀδικεῖν τούϛ τε νέουϛ

διαφθείροντα) and not acknowledging the gods that the city does, but some other new divinities (ἓτερα δὲ δαιμόνια καινά).

— Plato, Apology, 24b9


Some of our city DAIMONIA:

Students should learn C or Java or Lisp…

Web is for hobbyists…

You should write your own implementation of quick sort…

Project management is for „managers“…

UML is mightier than Zeus…

Design patterns are mightier than UML…

Test-driven development is some other new divinity…

Ruby on Rails is some other new divinity…

NoSQL databases are some other new divinities…

(etc ad nauseam)


Programming isa specific way of thinking.


Why Teach Programming (to non-programmers)?1


„To use a tool on a computer, you need do little more than

point and click; to create a tool, you must understand the

arcane art of computer programming“

— John Maeda, Creative Code


Literacy

(reading and writing)

Complexity

„Hack“


File.read('pride_and_prejudice.txt'). split(' '). sort. uniq

Literacy

To most of my students, this:

is an ultimate, OMG this is soooooo cool hack

Although it really does not „work“ that well. That’s part of the explanation.


Ruby as an „Ideal” Programming Language?2


There are only two hard things in Computer Science: cache invalidation and naming things.

— Phil Karlton


The limits of my language mean the limits of my world(Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt)

— Ludwig Wittgenstein, Tractatus Logico-Philosophicus 5.6


We use Ruby because it’s…

Expressive

Flexible and dynamic

Not tied to a specific paradigm

Well designed (cf. Enumerable)

Powerful(etc ad nauseam)

Ruby as an „Ideal” Programming Language?


All those reasons are validfor didactic purposes as well.


Of course… not only Ruby…



www.headfirstlabs.com/books/hfprog/


http://www.headfirstlabs.com/books/hfprog/

http://www.headfirstlabs.com/books/hfprog/

www.ericschmiedl.com/hacks/large-256.html

http://mit.edu/6.01http://news.ycombinator.com/item?id=530605

http://www.ericschmiedl.com/hacks/large-256.html

http://www.ericschmiedl.com/hacks/large-256.html

http://mit.edu/6.01

http://mit.edu/6.01

http://news.ycombinator.com/item?id=530605

http://news.ycombinator.com/item?id=530605


5.times do print "Hello. "end



Let’s start with the basics...



An algorithm is a sequence of well defined and finite instructions. It starts from an initial state and terminates in an end state.

— Wikipedia


1. Pour oil in the pan2. Light the gas3. Take some eggs4. ...

Algorithms and kitchen recipes


SIMPLE ALGORITHM EXAMPLE

Finding the largest number from unordered list

1. Let’s assume, that the first number in the list is the largest.

2. Let’s look on every other number in the list, in succession. If it’s larger then previous number, let’s write it down.

3. When we have stepped through all the numbers, the last number written down is the largest one.

http://en.wikipedia.org/wiki/Algorithm#Example

http://en.wikipedia.org/wiki/Algorithm%23Example

http://en.wikipedia.org/wiki/Algorithm%23Example


FORMAL DESCRIPTION IN ENGLISH

Input: A non‐empty list of numbers LOutput: The largest number in the list L

largest ← L0for each item in the list L≥1, do if the item > largest, then

largest ← the itemreturn largest



DESCRIPTION IN PROGRAMMING LANGUAGE

1 #include <stdio.h>2 #define SIZE 113 int main()4 {5 int input[SIZE] = {1, 5, 3, 95, 43, 56, 32, 90, 2, 4, 19};6 int largest = input[0];7 int i;8 for (i = 1; i < SIZE; i++) {9 if (input[i] > largest)10 largest = input[i];11 }12 printf("Largest number is: %d\n", largest);13 return 0;14 }

C




1 class MaxApp {2 public static void main (String args[]) {3 int[] input = {1, 5, 3, 95, 43, 56, 32, 90, 2, 4, 19};4 int largest = input[0];5 for (int i = 0; i < input.length; i++) {6 if (input[i] > largest)7 largest = input[i];8 }9 System.out.println("Largest number is: " + largest + "\n");10 }11 }

Java




1 input = [1, 5, 3, 95, 43, 56, 32, 90, 2, 4, 19]2 largest = input.first3 input.each do |i|4 largest = i if i > largest5 end6 print "Largest number is: #{largest} \n"

Ruby



1 input = [1, 5, 3, 95, 43, 56, 32, 90, 2, 4, 19]2 largest = input.first3 input.each do |i|4 largest = i if i > largest5 end6 print "Largest number is: #{largest} \n"

largest ← L0for each item in the list L≥1, do if the item > largest, then largest ← the itemreturn largest



What can we explain with this example?

‣ Input / Output‣ Variable‣ Basic composite data type: an array (a list of items)

‣ Iterating over collection‣ Block syntax‣ Conditions‣ String interpolation

# find_largest_number.rb

input = [3, 6, 9, 1]

largest = input.shift

input.each do |i|

largest = i if i > largest

end

print "Largest number is: #{largest} \n"


That’s... well, basic...


# Function definition:

def max(input)

largest = input.shift

input.each do |i|

largest = i if i > largest

end

return largest

end

# Usage:

puts max( [3, 6, 9, 1] )

# => 9

The concept of a function (method)…

BUT, YOU CAN EXPLAIN ALSO…


… the concept of polymorphydef max(*input) largest = input.shift input.each do |i| largest = i if i > largest end return largestend

# Usageputs max( 4, 3, 1 )puts max( 'lorem', 'ipsum', 'dolor' )puts max( Time.mktime(2010, 1, 1), Time.now, Time.mktime(1970, 1, 1) )

puts max( Time.now, 999 ) #=> (ArgumentError: comparison of Fixnum with Time failed)



… that you’re doing it wrong — most of the time :)

# Enumerable#maxputs [3, 6, 9, 1].max



Pick an example and stick with it

Switching contexts is distractingWhat’s the difference between “ and ‘ quote?

What does the @ mean in a @variable ?

„OMG what is a class and an object?“

WHAT I HAVE LEARNED


"hello".reverse

[1, 14, 7, 3].max

["banana", "lemon", "ananas"].size

["banana", "lemon", "ananas"].sort

["banana", "lemon", "ananas"].sort.last

["banana", "lemon", "ananas"].sort.last.capitalize

5.times do

print "Hello. "

end

Interactive Ruby console at http://tryruby.org

http://www.tryruby.org/

http://www.tryruby.org/


Great „one-click“ installer for Windows


Great resources, available for free

www.pine.fm/LearnToProgram (first edition)

http://pine.fm/LearnToProgram/

http://pine.fm/LearnToProgram/


Like, tooootaly excited!

Why’s (Poignant) Guide To Ruby

http://mislav.uniqpath.com/poignant-guide

http://mislav.uniqpath.com/poignant-guide


def sum(list) total = 0 for i in 0..list.size-1 total = total + list[i] end totalend

def sum(list) total = 0 list.each do |item| total += item end totalend

def test_sum_empty sum([]) == 0end

# ...

def sum(list) total = 0 list.each{|i| total += i} totalend

def sum(list) list.inject(0){|a,b| a+b}end

class Array def sum inject{|a,b| a+b} endend

describe "Enumerable objects should sum themselves" do

it 'should sum arrays of floats' do [1.0, 2.0, 3.0].sum.should == 6.0 end

# ...end

# ...

Ruby will grow with you

1

2

3

4

5

6

7

www.entish.org/wordpress/?p=707

(„The Evolution of a Ruby Programmer“)

http://www.entish.org/wordpress/?p=707

http://www.entish.org/wordpress/?p=707


If you’re teaching/training, try to learn something you’re really bad at.

‣ Playing a musical instrument‣ Drawing‣ Dancing‣ Martial arts

‣ …

It gives you the beginner’s perspective

WHAT I HAVE LEARNED


Web as a Platform3

www.shoooes.net

2009

http://www.shoooes.net


R.I.P. www.shoooes.net

2009














But wait! Almost all of us are doing web applications today.


Why web is a great platform?

Transparent: view-source all the waySimple to understandSimple and free development toolsLow barrier of entryExtensive documentationRich platform (HTML5, „jQuery“, …)Advanced development platforms (Rails, Django, …)Ubiquitous(etc ad nauseam)


All those reasons are validfor didactic purposes as well.


http://github.com/stunome/kiwi/

CODED LIVE IN CLASS, THEN CLEANED UP AND PUT ON GITHUB




Why a Wiki?

Well known and understood piece of software with minimal and well defined feature set (www.c2.com/cgi/wiki?WikiPrinciples)

Used on a daily basis (Wikipedia)

Feature set could be expanded based on individual skills

http://c2.com/cgi/wiki?WikiPrinciples

http://c2.com/cgi/wiki?WikiPrinciples


Sinatra.rb

www.sinatrarb.com

2010

http://www.sinatrarb.com

http://www.sinatrarb.com


Sinatra.rb

Why choose Sinatra?

Expose HTTP! GET / → get("/") { ... }

Simple to install and run $ ruby myapp.rb

Simple to write „Hello World“ applications


$ curl --include --verbose http://www.example.com

* About to connect() to example.com port 80 (#0)* Trying 192.0.32.10... connected* Connected to example.com (192.0.32.10) port 80 (#0)> GET / HTTP/1.1...< HTTP/1.1 200 OK...< <HTML><HEAD> <TITLE>Example Web Page</TITLE>...* Closing connection #0

Expose HTTP


Expose HTTP

# my_first_web_application.rb

require 'rubygems'require 'sinatra'

get '/' do "Hello, World!"end

get '/time' do Time.now.to_send


First „real code“ — saving pages

http://github.com/stunome/kiwi/commit/33fb87

.gitignore | 2 ++ application.rb | 22 ++++++++++++++++++++++ views/form.erb | 9 +++++++++ views/layout.erb | 12 ++++++++++++ 4 files changed, 45 insertions(+), 0 deletions(‐)



Spoiling the Youth With Rubyhttp://github.com/stunome/kiwi/commit/33fb87

Refactoring code to OOP (Page class)

application.rb | 4 +++‐ kiwi.rb | 7 +++++++ 2 files changed, 10 insertions(+), 1 deletions(‐)




www.pivotaltracker.com/projects/74202

Teaching real-world processes and tools

http://www.pivotaltracker.com/projects/74202

http://www.pivotaltracker.com/projects/74202


Teaching real-world processes and tools





The difference between theory and practice is bigger in practice then in theory.

(Jan L. A. van de Snepscheut or Yogi Berra, paraphrase)

http://en.wikiquote.org/wiki/Jan_L._A._van_de_Snepscheut

http://en.wikiquote.org/wiki/Jan_L._A._van_de_Snepscheut

http://en.wikiquote.org/wiki/Yogi_Berra

http://en.wikiquote.org/wiki/Yogi_Berra


Automated testing and test-driven development

Cucumber

Deployment (Heroku.com)

What I had no time to cover (alas)


A common curriculum for teaching Ruby(for inspiration, adaptation, discussion, …)

Code shared on GitHub

TeachingRuby (RailsBridge) (http://teachingkids.railsbridge.org)

Try Camping (http://github.com/judofyr/try-camping)

http://testfirst.org ?

What would be great to have

http://teachingkids.railsbridge.org

http://teachingkids.railsbridge.org

http://github.com/judofyr/try-camping

http://github.com/judofyr/try-camping

http://testfirst.org

http://testfirst.org

Questions!

spoiling the youth with ruby (euruko 2010)

Technology

ruby euruko

new divinity ruby

ideal programming language

largest number

programming language

spoiling humanities

programming language

previous number