Chapter Types

types/00.md

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+!SLIDE subsection
+# Data Types

types/01_nil.md

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+!SLIDE subsection
+# `nil`
+
+
 !SLIDE
-# nil
+# `nil`
+
+    @@@ Ruby
+    # nil is the Ruby value for null
+    var = nil
+
+    # Check if the value is nil
+    var.nil?
+    # => true
+
+    # Alternative version, almost never used
+    var == nil
+    # => true
+
+
+!SLIDE
+# `nil`
+
+    @@@ Ruby
+
+    # nil evaluates to false
+    nil ? true : false
+    # => false

types/02_boolean.md

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+!SLIDE subsection
+# Boolean
+
+
 !SLIDE
 # Boolean
+
+    @@@ Ruby
+    var = true
+
+    if var
+      # var is true
+    else
+      # var is false
+    end

types/03_string.md

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+!SLIDE subsection
+# String
+
+
+!SLIDE
+# String
+
+    @@@ Ruby
+    var = 'string'
+    var = "string"
+
+    var = %q{string}
+    var = %Q{string}
+
+    var = <<-EOS
+      long
+      string
+    EOS
+
+
+!SLIDE
+# String
+## The Ruby way
+
+    @@@ Ruby
+    # Rubyists do not use \ to escape
+    # because it makes the code hard to read
+    var = "<a href=\"\#hello\">I'm a tag</a>"
+
+    # They prefer a more natural syntax
+    var = %q{<a href="#hello">I'm a tag</a>}
+
+
+!SLIDE
+# String
+## Interpolation
+
+    @@@ Ruby
+    who = "world"
+
+    var = 'hello #{who}'
+    # => hello #{who}
+
+    var = "hello #{who}"
+    # => hello world
+
+    var = %q{hello #{who}}
+    # => hello #{who}
+
+    var = %Q{hello #{who}}
+    # => hello world
+
+
+!SLIDE
+# String
+## Escape sequences
+
+    @@@ Ruby
+
+    var = 'hello\nworld'
+    # => hello\nworld
+
+    var = "hello\nnworld"
+    # => hello
+         world
+
+    var = %q{hello\nnworld}
+    # => hello\nnworld
+
+    var = %Q{hello\nnworld}
+    # => hello
+         world
+
+
+!SLIDE
+# String
+## % Notation
+
+    @@@ Ruby
+
+    "I love %s" % "Ruby"
+    # => "I love Ruby"
+
+    "I prefer %s over %s" % ["Ruby", "Java"]
+    # => "I prefer Ruby over Java"
+
+    vars = { :a => "Ruby", :b => "Java" }
+    "I prefer %{a} over %{b}. I love %{a}!" % vars
+    # => "I prefer Ruby over Java. I love Ruby!"
+
+
 !SLIDE
 # String
+
+    @@@ Ruby
+
+    # empty string evaluates to true
+    "" ? true : false
+    # => true
+
+    # not-empty string evaluates to true
+    "string" ? true : false
+    # => true

types/04_symbol.md

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+!SLIDE subsection
+# Sumbol
+
+
+!SLIDE
+# Symbol
+
+    @@@ Ruby
+    var = :foo
+
+    var
+    # => :foo
+
+    var.to_s
+    # => "foo"
+
+
+!SLIDE
+# Symbol
+
+    @@@ Ruby
+    :foo == :"foo"
+    # => true
+
+    :foo == "foo".intern
+    # => true
+
+    :foo == "foo".to_sym
+    # => true
+
+
+!SLIDE
+# Symbol
+
+    @@@ Ruby
+    var = "Simone"
+
+    var.respond_to?(:upcase)
+    # => true
+
+    var.send(:upcase)
+    # => "SIMONE"

types/05_number.md

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+!SLIDE subsection
+# Number
+
+
+!SLIDE
+# Number
+
+    @@@ Ruby
+    # Fixnum
+    1
+    -1
+
+    # Float
+    1.0
+
+    # The following two objects are equal
+    1000000
+    1_000_000
+
+
+!SLIDE
+# Number
+
+    @@@ Ruby
+
+    # 0 evaluates to true
+    0 ? true : false
+    # => true
+
+    # not-0 evaluates to true
+    10 ? true : false
+    # => true

types/06_array.md

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+!SLIDE subsection
+# Array
+
+
+!SLIDE
+# Array
+
+    @@@ Ruby
+    var = Array.new
+    # => []
+
+    var = ["foo", "bar", "baz"]
+    # => ["foo", "bar", "baz"]
+
+    var = [
+           "foo",
+           "bar",
+           "baz",
+           ]
+    # => ["foo", "bar", "baz"]
+
+    var = %w( foo bar baz )
+    # => ["foo", "bar", "baz"]
+
+
+!SLIDE
+# Array
+
+    @@@ Ruby
+    var = ["foo", 0, "baz"]
+
+    var = ["foo", ["bar", "baz"]]
+
+
+!SLIDE
+# Array
+
+    @@@ Ruby
+    var1 = %w( yellow orange )
+    var2 = %w( red yellow )
+
+    var1.size
+    # => 2
+
+    var1[1] = "blue"
+    # => blue
+
+    var1 + var2
+    # => ["yellow", "blue", "red", "yellow"]
+
+
+!SLIDE
+# Enumerable
+
+    @@@ Ruby
+    var1 = %w( yellow orange red )
+
+    var1.each { |color| p(color) }
+    # => yellow
+    # => orange
+    # => red
+
+    var1.map { |color| color.upcase }
+    # => ["YELLOW", "ORANGE", "RED"]
+
+    var1.select { |color| color.size == 3 }
+    # => ["red"]

types/07_hash.md

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+!SLIDE subsection
+# Hash
+
+
+!SLIDE
+# Hash
+
+    @@@ Ruby
+    var = {}
+    # => {}
+
+    var = { "foo" => 1, "bar" => 2 }
+    var = { :foo => 1, :bar => 2 }
+
+
+!SLIDE
+# Hash
+
+    @@@ Ruby
+    var = { :foo => 1, :bar => 2 }
+
+    var[:baz]
+    # => nil
+
+    var[:foo]
+    # => 1
+
+    var[:foo] = 2
+    # => 2
+
+    var["foo"]
+    # => nil