Initial WIP commit for ruby

ruby.html.markdown

@@ -0,0 +1,202 @@
+---
+language: ruby
+author: David Underwood
+author_url: http://theflyingdeveloper.com
+---
+
+```ruby
+# This is a comment
+
+=begin
+This is a multiline comment
+No-one uses them
+You shouldn't either
+=end
+
+
+3 #=> 3
+
+
+# Some basic arithmetic
+1 + 1 #=> 2
+8 - 1 #=> 7
+10 * 2 #=> 20
+35 / 5 #=> 7
+
+# Special values
+nil #=> Nothing to see here
+true #=> truth
+false #=> falsehood
+
+# Equality
+1 == 1 #=> true
+2 == 1 #=> false
+
+# Inequality
+1 != 1 #=> false
+2 != 1 #=> true
+!true  #=> false
+!false #=> true
+
+# More comparisons
+1 < 10 #=> True
+1 > 10 #=> False
+2 <= 2 #=> True
+2 >= 2 #=> True
+
+'I am a string'
+"I am a string too"
+
+placeholder = "use variables inline"
+"I can #{placeholder} when using double quoted strings"
+#=> "I can use variables inline when using double quoted strings"
+
+
+# print to the output
+puts "I'm printing!"
+
+# Variables
+x = 25 #=> 25
+
+# Note that assignment returns the value assigned
+# This means you can do multiple assignment:
+
+x = y = 10 #=> 10
+x #=> 10
+y #=> 10
+
+# By convention, use snake_case for variable names
+snake_case = true
+
+# Use descriptive variable names
+path_to_project_root = '/good/name/'
+path = '/bad/name/'
+
+# Arrays
+
+# This is an array
+[1, 2, 3, 4, 5] #=> [1, 2, 3, 4, 5]
+
+# Arrays can contain different types of items
+
+array = [1, "hello", false] #=> => [1, "hello", false]
+
+# Arrays can be indexed
+# From the front
+array[0] #=> 1
+array[12] #=> nil
+
+# From the end
+array[-1] #=> 5
+
+# With a start and end index
+array[2, 4] #=> [3, 4, 5]
+
+# Or with a range
+array[1..3] #=> [2, 3, 4]
+
+# Add to the end of an array like this
+array << 6 #=> [1, 2, 3, 4, 5, 6]
+
+# Or like this
+array.push 7 #=> [1, 2, 3, 4, 5, 6, 7]
+
+# Or to the beginning like this
+array.unshift 0 #=> [0, 1, 2, 3, 4, 5, 6, 7]
+
+# Remove the first item in an array
+
+array.shift #=> [1, 2, 3, 4, 5, 6, 7]
+
+# Or the last
+
+array.pop #=> [1, 2, 3, 4, 5, 6]
+
+# Note that push and pop do the opposite of each other
+# Shift and unshift are the same.
+
+# Control structures
+
+if true
+  "if statement"
+elsif false
+ "else if, optional"
+else
+ "else, also optional"
+end
+
+for counter in 1..5
+  puts "iteration #{counter}"
+end
+#=> iteration 1
+#=> iteration 2
+#=> iteration 3
+#=> iteration 4
+#=> iteration 5
+
+# HOWEVER
+# No-one uses for loops
+# Use `each` instead, like this:
+
+(1..5).each do |counter|
+  puts "iteration #{counter}"
+end
+#=> iteration 1
+#=> iteration 2
+#=> iteration 3
+#=> iteration 4
+#=> iteration 5
+
+counter = 1
+while counter <= 5 do
+  puts "iteration #{counter}"
+end
+#=> iteration 1
+#=> iteration 2
+#=> iteration 3
+#=> iteration 4
+#=> iteration 5
+
+grade = 'B'
+case grade
+when 'A'
+  puts "way to go kiddo"
+when 'B'
+  puts "Better luck next time"
+when 'C'
+  puts "You can do better"
+when 'D'
+  puts "Scraping through"
+when 'F'
+  puts "You failed!"
+
+
+# Functions
+
+def double(x)
+  x * 2
+end
+
+# Functions (and all blocks) implcitly return the value of the last statement
+double(2) #=> 4
+
+# Parentheses are optional where the result is unambiguous
+double 3 #=> 6
+
+double double 3 #=> 12
+
+def sum(x,y)
+  x + y
+end
+
+# Method arguments are separated by a comma
+sum 3, 4 #=> 7
+
+sum sum(3,4), 5 #=> 12
+
+# yield
+# All methods have an implicit, optional block parameter
+# it can be called with the 'yield' keyword
+
+
+```