Merge branch 'master' of https://github.com/torgeek/learnxinyminutes-docs

1 files changed, 462 insertions, 363 deletions

diff --git a/julia.html.markdown b/julia.html.markdown
index 5b3f6fd8..4d8eb497 100644
--- a/julia.html.markdown
+++ b/julia.html.markdown
@@ -2,17 +2,18 @@
 language: Julia
 contributors:
     - ["Leah Hanson", "http://leahhanson.us"]
-    - ["Pranit Bauva", "http://github.com/pranitbauva1997"]
+    - ["Pranit Bauva", "https://github.com/pranitbauva1997"]
+    - ["Daniel YC Lin", "https://github.com/dlintw"]
 filename: learnjulia.jl
 ---
 
 Julia is a new homoiconic functional language focused on technical computing.
-While having the full power of homoiconic macros, first-class functions, and low-level control, Julia is as easy to learn and use as Python.
+While having the full power of homoiconic macros, first-class functions,
+and low-level control, Julia is as easy to learn and use as Python.
 
-This is based on Julia 0.4.
-
-```ruby
+This is based on Julia version 1.0.0.
 
+```julia
 # Single line comments start with a hash (pound) symbol.
 #= Multiline comments can be written
    by putting '#=' before the text  and '=#'
@@ -26,38 +27,45 @@ This is based on Julia 0.4.
 # Everything in Julia is an expression.
 
 # There are several basic types of numbers.
-3 # => 3 (Int64)
-3.2 # => 3.2 (Float64)
-2 + 1im # => 2 + 1im (Complex{Int64})
-2//3 # => 2//3 (Rational{Int64})
+typeof(3)       # => Int64
+typeof(3.2)     # => Float64
+typeof(2 + 1im) # => Complex{Int64}
+typeof(2 // 3)  # => Rational{Int64}
 
 # All of the normal infix operators are available.
-1 + 1 # => 2
-8 - 1 # => 7
-10 * 2 # => 20
-35 / 5 # => 7.0
-5 / 2 # => 2.5 # dividing an Int by an Int always results in a Float
-div(5, 2) # => 2 # for a truncated result, use div
-5 \ 35 # => 7.0
-2 ^ 2 # => 4 # power, not bitwise xor
-12 % 10 # => 2
+1 + 1      # => 2
+8 - 1      # => 7
+10 * 2     # => 20
+35 / 5     # => 7.0
+10 / 2     # => 5.0  # dividing integers always results in a Float64
+div(5, 2)  # => 2    # for a truncated result, use div
+5 \ 35     # => 7.0
+2^2        # => 4    # power, not bitwise xor
+12 % 10    # => 2
 
 # Enforce precedence with parentheses
-(1 + 3) * 2 # => 8
+(1 + 3) * 2  # => 8
+
+# Julia (unlike Python for instance) has integer under/overflow
+10^19      # => -8446744073709551616
+# use bigint or floating point to avoid this
+big(10)^19 # => 10000000000000000000
+1e19       # => 1.0e19
+10.0^19    # => 1.0e19
 
 # Bitwise Operators
-~2 # => -3   # bitwise not
-3 & 5 # => 1 # bitwise and
-2 | 4 # => 6 # bitwise or
-2 $ 4 # => 6 # bitwise xor
-2 >>> 1 # => 1 # logical shift right
-2 >> 1  # => 1 # arithmetic shift right
-2 << 1  # => 4 # logical/arithmetic shift left
-
-# You can use the bits function to see the binary representation of a number.
-bits(12345)
+~2         # => -3 # bitwise not
+3 & 5      # => 1  # bitwise and
+2 | 4      # => 6  # bitwise or
+xor(2, 4)  # => 6  # bitwise xor
+2 >>> 1    # => 1  # logical shift right
+2 >> 1     # => 1  # arithmetic shift right
+2 << 1     # => 4  # logical/arithmetic shift left
+
+# Use the bitstring function to see the binary representation of a number.
+bitstring(12345)
 # => "0000000000000000000000000000000000000000000000000011000000111001"
-bits(12345.0)
+bitstring(12345.0)
 # => "0100000011001000000111001000000000000000000000000000000000000000"
 
 # Boolean values are primitives
@@ -65,72 +73,75 @@ true
 false
 
 # Boolean operators
-!true # => false
-!false # => true
-1 == 1 # => true
-2 == 1 # => false
-1 != 1 # => false
-2 != 1 # => true
-1 < 10 # => true
-1 > 10 # => false
-2 <= 2 # => true
-2 >= 2 # => true
-# Comparisons can be chained
-1 < 2 < 3 # => true
-2 < 3 < 2 # => false
+!true   # => false
+!false  # => true
+1 == 1  # => true
+2 == 1  # => false
+1 != 1  # => false
+2 != 1  # => true
+1 < 10  # => true
+1 > 10  # => false
+2 <= 2  # => true
+2 >= 2  # => true
+# Comparisons can be chained, like in Python but unlike many other languages
+1 < 2 < 3  # => true
+2 < 3 < 2  # => false
 
 # Strings are created with "
 "This is a string."
 
-# Julia has several types of strings, including ASCIIString and UTF8String.
-# More on this in the Types section.
-
 # Character literals are written with '
 'a'
 
-# Some strings can be indexed like an array of characters
-"This is a string"[1] # => 'T' # Julia indexes from 1
-# However, this is will not work well for UTF8 strings,
-# so iterating over strings is recommended (map, for loops, etc).
+# Strings are UTF8 encoded, so strings like "π" or "☃" are not directly equivalent
+# to an array of single characters.
+# Only if they contain only ASCII characters can they be safely indexed.
+ascii("This is a string")[1]    # => 'T'
+# => 'T': ASCII/Unicode U+0054 (category Lu: Letter, uppercase)
+# Beware, Julia indexes everything from 1 (like MATLAB), not 0 (like most languages).
+# Otherwise, iterating over strings is recommended (map, for loops, etc).
 
-# $ can be used for string interpolation:
+# String can be compared lexicographically, in dictionnary order:
+"good" > "bye"   # => true
+"good" == "good" # => true
+"1 + 2 = 3" == "1 + 2 = $(1 + 2)" # => true
+
+# $(..) can be used for string interpolation:
 "2 + 2 = $(2 + 2)" # => "2 + 2 = 4"
 # You can put any Julia expression inside the parentheses.
 
-# Another way to format strings is the printf macro.
-@printf "%d is less than %f" 4.5 5.3 # 5 is less than 5.300000
-
 # Printing is easy
-println("I'm Julia. Nice to meet you!")
+println("I'm Julia. Nice to meet you!")  # => I'm Julia. Nice to meet you!
+
+# Another way to format strings is the printf macro from the stdlib Printf.
+using Printf   # this is how you load (or import) a module
+@printf "%d is less than %f\n" 4.5 5.3   # => 5 is less than 5.300000
 
-# String can be compared lexicographically
-"good" > "bye" # => true
-"good" == "good" # => true
-"1 + 2 = 3" == "1 + 2 = $(1+2)" # => true
 
 ####################################################
 ## 2. Variables and Collections
 ####################################################
 
 # You don't declare variables before assigning to them.
-some_var = 5 # => 5
-some_var # => 5
+someVar = 5  # => 5
+someVar      # => 5
 
 # Accessing a previously unassigned variable is an error
 try
-    some_other_var # => ERROR: some_other_var not defined
+    someOtherVar  # => ERROR: UndefVarError: someOtherVar not defined
 catch e
     println(e)
 end
 
 # Variable names start with a letter or underscore.
 # After that, you can use letters, digits, underscores, and exclamation points.
-SomeOtherVar123! = 6 # => 6
+SomeOtherVar123! = 6  # => 6
 
 # You can also use certain unicode characters
-☃ = 8 # => 8
-# These are especially handy for mathematical notation
-2 * π # => 6.283185307179586
+# here ☃ is a Unicode 'snowman' characters, see http://emojipedia.org/%E2%98%83%EF%B8%8F if it displays wrongly here
+☃ = 8  # => 8
+# These are especially handy for mathematical notation, like the constant π
+2 * π  # => 6.283185307179586
 
 # A note on naming conventions in Julia:
 #
@@ -147,250 +158,283 @@ SomeOtherVar123! = 6 # => 6
 #   functions are sometimes called mutating functions or in-place functions.
 
 # Arrays store a sequence of values indexed by integers 1 through n:
-a = Int64[] # => 0-element Int64 Array
+a = Int64[] # => 0-element Array{Int64,1}
 
 # 1-dimensional array literals can be written with comma-separated values.
-b = [4, 5, 6] # => 3-element Int64 Array: [4, 5, 6]
-b = [4; 5; 6] # => 3-element Int64 Array: [4, 5, 6]
-b[1] # => 4
-b[end] # => 6
+b = [4, 5, 6] # => 3-element Array{Int64,1}: [4, 5, 6]
+b = [4; 5; 6] # => 3-element Array{Int64,1}: [4, 5, 6]
+b[1]    # => 4
+b[end]  # => 6
 
 # 2-dimensional arrays use space-separated values and semicolon-separated rows.
-matrix = [1 2; 3 4] # => 2x2 Int64 Array: [1 2; 3 4]
+matrix = [1 2; 3 4] # => 2×2 Array{Int64,2}: [1 2; 3 4]
 
-# Arrays of a particular Type
-b = Int8[4, 5, 6] # => 3-element Int8 Array: [4, 5, 6]
+# Arrays of a particular type
+b = Int8[4, 5, 6] # => 3-element Array{Int8,1}: [4, 5, 6]
 
 # Add stuff to the end of a list with push! and append!
-push!(a,1)     # => [1]
-push!(a,2)     # => [1,2]
-push!(a,4)     # => [1,2,4]
-push!(a,3)     # => [1,2,4,3]
-append!(a,b) # => [1,2,4,3,4,5,6]
+# By convention, the exclamation mark '!' is appended to names of functions
+# that modify their arguments
+push!(a, 1)    # => [1]
+push!(a, 2)    # => [1,2]
+push!(a, 4)    # => [1,2,4]
+push!(a, 3)    # => [1,2,4,3]
+append!(a, b)  # => [1,2,4,3,4,5,6]
 
 # Remove from the end with pop
-pop!(b)        # => 6 and b is now [4,5]
+pop!(b)  # => 6
+b # => [4,5]
 
 # Let's put it back
-push!(b,6)   # b is now [4,5,6] again.
+push!(b, 6)  # => [4,5,6]
+b # => [4,5,6]
 
-a[1] # => 1 # remember that Julia indexes from 1, not 0!
+a[1]  # => 1  # remember that Julia indexes from 1, not 0!
 
 # end is a shorthand for the last index. It can be used in any
 # indexing expression
-a[end] # => 6
+a[end]  # => 6
 
-# we also have shift and unshift
-shift!(a) # => 1 and a is now [2,4,3,4,5,6]
-unshift!(a,7) # => [7,2,4,3,4,5,6]
+# we also have popfirst! and pushfirst!
+popfirst!(a)  # => 1 
+a # => [2,4,3,4,5,6]
+pushfirst!(a, 7)  # => [7,2,4,3,4,5,6]
+a # => [7,2,4,3,4,5,6]
 
 # Function names that end in exclamations points indicate that they modify
 # their argument.
-arr = [5,4,6] # => 3-element Int64 Array: [5,4,6]
-sort(arr) # => [4,5,6]; arr is still [5,4,6]
-sort!(arr) # => [4,5,6]; arr is now [4,5,6]
+arr = [5,4,6]  # => 3-element Array{Int64,1}: [5,4,6]
+sort(arr)      # => [4,5,6]
+arr            # => [5,4,6]
+sort!(arr)     # => [4,5,6]
+arr            # => [4,5,6]
 
 # Looking out of bounds is a BoundsError
 try
-    a[0] # => ERROR: BoundsError() in getindex at array.jl:270
-    a[end+1] # => ERROR: BoundsError() in getindex at array.jl:270
+    a[0] 
+    # => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at 
+    # index [0]
+    # => Stacktrace:
+    # =>  [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731
+    # =>  [2] top-level scope at none:0
+    # =>  [3] ...
+    # => in expression starting at ...\LearnJulia.jl:180
+    a[end + 1] 
+    # => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at 
+    # index [8]
+    # => Stacktrace:
+    # =>  [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731
+    # =>  [2] top-level scope at none:0
+    # =>  [3] ...
+    # => in expression starting at ...\LearnJulia.jl:188
 catch e
     println(e)
 end
 
 # Errors list the line and file they came from, even if it's in the standard
-# library. If you built Julia from source, you can look in the folder base
-# inside the julia folder to find these files.
+# library. You can look in the folder share/julia inside the julia folder to
+# find these files.
 
 # You can initialize arrays from ranges
-a = [1:5;] # => 5-element Int64 Array: [1,2,3,4,5]
+a = [1:5;]  # => 5-element Array{Int64,1}: [1,2,3,4,5]
+a2 = [1:5]  # => 1-element Array{UnitRange{Int64},1}: [1:5]
 
 # You can look at ranges with slice syntax.
-a[1:3] # => [1, 2, 3]
-a[2:end] # => [2, 3, 4, 5]
+a[1:3]    # => [1, 2, 3]
+a[2:end]  # => [2, 3, 4, 5]
 
 # Remove elements from an array by index with splice!
 arr = [3,4,5]
-splice!(arr,2) # => 4 ; arr is now [3,5]
+splice!(arr, 2) # => 4 
+arr # => [3,5]
 
 # Concatenate lists with append!
 b = [1,2,3]
-append!(a,b) # Now a is [1, 2, 3, 4, 5, 1, 2, 3]
+append!(a, b) # => [1, 2, 3, 4, 5, 1, 2, 3]
+a # => [1, 2, 3, 4, 5, 1, 2, 3]
 
 # Check for existence in a list with in
-in(1, a) # => true
+in(1, a)  # => true
 
 # Examine the length with length
-length(a) # => 8
+length(a)  # => 8
 
 # Tuples are immutable.
-tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
+tup = (1, 2, 3)  # => (1,2,3)
+typeof(tup) # => Tuple{Int64,Int64,Int64}
 tup[1] # => 1
-try:
-    tup[1] = 3 # => ERROR: no method setindex!((Int64,Int64,Int64),Int64,Int64)
+try
+    tup[1] = 3  
+    # => ERROR: MethodError: no method matching 
+    # setindex!(::Tuple{Int64,Int64,Int64}, ::Int64, ::Int64)
 catch e
     println(e)
 end
 
-# Many list functions also work on tuples
+# Many array functions also work on tuples
 length(tup) # => 3
-tup[1:2] # => (1,2)
-in(2, tup) # => true
+tup[1:2]    # => (1,2)
+in(2, tup)  # => true
 
 # You can unpack tuples into variables
-a, b, c = (1, 2, 3) # => (1,2,3)  # a is now 1, b is now 2 and c is now 3
+a, b, c = (1, 2, 3)  # => (1,2,3)  
+a  # => 1
+b  # => 2
+c  # => 3
 
 # Tuples are created even if you leave out the parentheses
-d, e, f = 4, 5, 6 # => (4,5,6)
+d, e, f = 4, 5, 6  # => (4,5,6)
+d  # => 4
+e  # => 5
+f  # => 6
 
 # A 1-element tuple is distinct from the value it contains
 (1,) == 1 # => false
-(1) == 1 # => true
+(1) == 1  # => true
 
 # Look how easy it is to swap two values
-e, d = d, e  # => (5,4) # d is now 5 and e is now 4
-
+e, d = d, e  # => (5,4) 
+d  # => 5
+e  # => 4
 
 # Dictionaries store mappings
-empty_dict = Dict() # => Dict{Any,Any}()
+emptyDict = Dict()  # => Dict{Any,Any} with 0 entries
 
 # You can create a dictionary using a literal
-filled_dict = Dict("one"=> 1, "two"=> 2, "three"=> 3)
-# => Dict{ASCIIString,Int64}
+filledDict = Dict("one" => 1, "two" => 2, "three" => 3)
+# => Dict{String,Int64} with 3 entries:
+# =>  "two" => 2, "one" => 1, "three" => 3
 
 # Look up values with []
-filled_dict["one"] # => 1
+filledDict["one"]  # => 1
 
 # Get all keys
-keys(filled_dict)
-# => KeyIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
+keys(filledDict)
+# => Base.KeySet for a Dict{String,Int64} with 3 entries. Keys:
+# =>  "two", "one", "three"
 # Note - dictionary keys are not sorted or in the order you inserted them.
 
 # Get all values
-values(filled_dict)
-# => ValueIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
+values(filledDict)
+# => Base.ValueIterator for a Dict{String,Int64} with 3 entries. Values: 
+# =>  2, 1, 3
 # Note - Same as above regarding key ordering.
 
 # Check for existence of keys in a dictionary with in, haskey
-in(("one" => 1), filled_dict) # => true
-in(("two" => 3), filled_dict) # => false
-haskey(filled_dict, "one") # => true
-haskey(filled_dict, 1) # => false
+in(("one" => 1), filledDict)  # => true
+in(("two" => 3), filledDict)  # => false
+haskey(filledDict, "one")     # => true
+haskey(filledDict, 1)         # => false
 
 # Trying to look up a non-existent key will raise an error
 try
-    filled_dict["four"] # => ERROR: key not found: four in getindex at dict.jl:489
+    filledDict["four"]  # => ERROR: KeyError: key "four" not found
 catch e
     println(e)
 end
 
 # Use the get method to avoid that error by providing a default value
-# get(dictionary,key,default_value)
-get(filled_dict,"one",4) # => 1
-get(filled_dict,"four",4) # => 4
+# get(dictionary, key, defaultValue)
+get(filledDict, "one", 4)   # => 1
+get(filledDict, "four", 4)  # => 4
 
 # Use Sets to represent collections of unordered, unique values
-empty_set = Set() # => Set{Any}()
+emptySet = Set()  # => Set(Any[])
 # Initialize a set with values
-filled_set = Set([1,2,2,3,4]) # => Set{Int64}(1,2,3,4)
+filledSet = Set([1, 2, 2, 3, 4])  # => Set([4, 2, 3, 1])
 
 # Add more values to a set
-push!(filled_set,5) # => Set{Int64}(5,4,2,3,1)
+push!(filledSet, 5)  # => Set([4, 2, 3, 5, 1])
 
 # Check if the values are in the set
-in(2, filled_set) # => true
-in(10, filled_set) # => false
+in(2, filledSet)   # => true
+in(10, filledSet)  # => false
 
 # There are functions for set intersection, union, and difference.
-other_set = Set([3, 4, 5, 6]) # => Set{Int64}(6,4,5,3)
-intersect(filled_set, other_set) # => Set{Int64}(3,4,5)
-union(filled_set, other_set) # => Set{Int64}(1,2,3,4,5,6)
-setdiff(Set([1,2,3,4]),Set([2,3,5])) # => Set{Int64}(1,4)
-
+otherSet = Set([3, 4, 5, 6])         # => Set([4, 3, 5, 6])
+intersect(filledSet, otherSet)      # => Set([4, 3, 5])
+union(filledSet, otherSet)          # => Set([4, 2, 3, 5, 6, 1])
+setdiff(Set([1,2,3,4]), Set([2,3,5])) # => Set([4, 1])
 
 ####################################################
 ## 3. Control Flow
 ####################################################
 
 # Let's make a variable
-some_var = 5
+someVar = 5
 
 # Here is an if statement. Indentation is not meaningful in Julia.
-if some_var > 10
-    println("some_var is totally bigger than 10.")
-elseif some_var < 10    # This elseif clause is optional.
-    println("some_var is smaller than 10.")
+if someVar > 10
+    println("someVar is totally bigger than 10.")
+elseif someVar < 10    # This elseif clause is optional.
+    println("someVar is smaller than 10.")
 else                    # The else clause is optional too.
-    println("some_var is indeed 10.")
+    println("someVar is indeed 10.")
 end
 # => prints "some var is smaller than 10"
 
-
 # For loops iterate over iterables.
 # Iterable types include Range, Array, Set, Dict, and AbstractString.
-for animal=["dog", "cat", "mouse"]
+for animal = ["dog", "cat", "mouse"]
     println("$animal is a mammal")
-    # You can use $ to interpolate variables or expression into strings
+    # You can use $ to interpolate variables or expression into strings.
+    # In this special case, no need for parenthesis: $animal and $(animal) give the same
 end
-# prints:
-#    dog is a mammal
-#    cat is a mammal
-#    mouse is a mammal
+# => dog is a mammal
+# => cat is a mammal
+# => mouse is a mammal
 
 # You can use 'in' instead of '='.
 for animal in ["dog", "cat", "mouse"]
     println("$animal is a mammal")
 end
-# prints:
-#    dog is a mammal
-#    cat is a mammal
-#    mouse is a mammal
+# => dog is a mammal
+# => cat is a mammal
+# => mouse is a mammal
 
-for a in Dict("dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal")
-    println("$(a[1]) is a $(a[2])")
+for pair in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
+    from, to = pair
+    println("$from is a $to")
 end
-# prints:
-#    dog is a mammal
-#    cat is a mammal
-#    mouse is a mammal
+# => mouse is a mammal
+# => cat is a mammal
+# => dog is a mammal
 
-for (k,v) in Dict("dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal")
+for (k, v) in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
     println("$k is a $v")
 end
-# prints:
-#    dog is a mammal
-#    cat is a mammal
-#    mouse is a mammal
+# => mouse is a mammal
+# => cat is a mammal
+# => dog is a mammal
 
 # While loops loop while a condition is true
-x = 0
-while x < 4
-    println(x)
-    x += 1  # Shorthand for x = x + 1
+let x = 0
+    while x < 4
+        println(x)
+        x += 1  # Shorthand for in place increment: x = x + 1
+    end
 end
-# prints:
-#   0
-#   1
-#   2
-#   3
+# => 0
+# => 1
+# => 2
+# => 3
 
 # Handle exceptions with a try/catch block
 try
-   error("help")
+    error("help")
 catch e
-   println("caught it $e")
+    println("caught it $e")
 end
 # => caught it ErrorException("help")
 
-
 ####################################################
 ## 4. Functions
 ####################################################
 
 # The keyword 'function' creates new functions
-#function name(arglist)
-#  body...
-#end
+# function name(arglist)
+#   body...
+# end
 function add(x, y)
     println("x is $x and y is $y")
 
@@ -398,15 +442,17 @@ function add(x, y)
     x + y
 end
 
-add(5, 6) # => 11 after printing out "x is 5 and y is 6"
+add(5, 6)
+# => x is 5 and y is 6
+# => 11
 
 # Compact assignment of functions
-f_add(x, y) = x + y # => "f (generic function with 1 method)"
-f_add(3, 4) # => 7
+f_add(x, y) = x + y  # => f_add (generic function with 1 method)
+f_add(3, 4)  # => 7
 
 # Function can also return multiple values as tuple
-f(x, y) = x + y, x - y
-f(3, 4) # => (7, -1)
+fn(x, y) = x + y, x - y # => fn (generic function with 1 method)
+fn(3, 4)  # => (7, -1)
 
 # You can define functions that take a variable number of
 # positional arguments
@@ -416,54 +462,56 @@ function varargs(args...)
 end
 # => varargs (generic function with 1 method)
 
-varargs(1,2,3) # => (1,2,3)
+varargs(1, 2, 3)  # => (1,2,3)
 
 # The ... is called a splat.
 # We just used it in a function definition.
 # It can also be used in a function call,
 # where it will splat an Array or Tuple's contents into the argument list.
-add([5,6]...) # this is equivalent to add(5,6)
+add([5,6]...)  # this is equivalent to add(5,6)
 
-x = (5,6)     # => (5,6)
-add(x...)     # this is equivalent to add(5,6)
+x = (5, 6)  # => (5,6)
+add(x...)  # this is equivalent to add(5,6)
 
 
 # You can define functions with optional positional arguments
-function defaults(a,b,x=5,y=6)
+function defaults(a, b, x=5, y=6)
     return "$a $b and $x $y"
 end
+# => defaults (generic function with 3 methods)
 
-defaults('h','g') # => "h g and 5 6"
-defaults('h','g','j') # => "h g and j 6"
-defaults('h','g','j','k') # => "h g and j k"
+defaults('h', 'g')  # => "h g and 5 6"
+defaults('h', 'g', 'j')  # => "h g and j 6"
+defaults('h', 'g', 'j', 'k')  # => "h g and j k"
 try
-    defaults('h') # => ERROR: no method defaults(Char,)
-    defaults() # => ERROR: no methods defaults()
+    defaults('h')  # => ERROR: MethodError: no method matching defaults(::Char)
+    defaults()  # => ERROR: MethodError: no method matching defaults()
 catch e
     println(e)
 end
 
 # You can define functions that take keyword arguments
-function keyword_args(;k1=4,name2="hello") # note the ;
-    return Dict("k1"=>k1,"name2"=>name2)
+function keyword_args(;k1=4, name2="hello")  # note the ;
+    return Dict("k1" => k1, "name2" => name2)
 end
+# => keyword_args (generic function with 1 method)
 
-keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4]
-keyword_args(k1="mine") # => ["k1"=>"mine","name2"=>"hello"]
-keyword_args() # => ["name2"=>"hello","k1"=>4]
+keyword_args(name2="ness")  # => ["name2"=>"ness", "k1"=>4]
+keyword_args(k1="mine")     # => ["name2"=>"hello", "k1"=>"mine"]
+keyword_args()              # => ["name2"=>"hello", "k1"=>4]
 
 # You can combine all kinds of arguments in the same function
-function all_the_args(normal_arg, optional_positional_arg=2; keyword_arg="foo")
-    println("normal arg: $normal_arg")
-    println("optional arg: $optional_positional_arg")
-    println("keyword arg: $keyword_arg")
+function all_the_args(normalArg, optionalPositionalArg=2; keywordArg="foo")
+    println("normal arg: $normalArg")
+    println("optional arg: $optionalPositionalArg")
+    println("keyword arg: $keywordArg")
 end
+# => all_the_args (generic function with 2 methods)
 
-all_the_args(1, 3, keyword_arg=4)
-# prints:
-#   normal arg: 1
-#   optional arg: 3
-#   keyword arg: 4
+all_the_args(1, 3, keywordArg=4)
+# => normal arg: 1
+# => optional arg: 3
+# => keyword arg: 4
 
 # Julia has first class functions
 function create_adder(x)
@@ -472,14 +520,16 @@ function create_adder(x)
     end
     return adder
 end
+# => create_adder (generic function with 1 method)
 
 # This is "stabby lambda syntax" for creating anonymous functions
-(x -> x > 2)(3) # => true
+(x -> x > 2)(3)  # => true
 
 # This function is identical to create_adder implementation above.
 function create_adder(x)
     y -> x + y
 end
+# => create_adder (generic function with 1 method)
 
 # You can also name the internal function, if you want
 function create_adder(x)
@@ -488,18 +538,21 @@ function create_adder(x)
     end
     adder
 end
+# => create_adder (generic function with 1 method)
 
-add_10 = create_adder(10)
+add_10 = create_adder(10) # => (::getfield(Main, Symbol("#adder#11")){Int64}) 
+                          # (generic function with 1 method)
 add_10(3) # => 13
 
 
 # There are built-in higher order functions
-map(add_10, [1,2,3]) # => [11, 12, 13]
-filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
+map(add_10, [1,2,3])  # => [11, 12, 13]
+filter(x -> x > 5, [3, 4, 5, 6, 7])  # => [6, 7]
 
-# We can use list comprehensions for nicer maps
-[add_10(i) for i=[1, 2, 3]] # => [11, 12, 13]
-[add_10(i) for i in [1, 2, 3]] # => [11, 12, 13]
+# We can use list comprehensions
+[add_10(i) for i = [1, 2, 3]]   # => [11, 12, 13]
+[add_10(i) for i in [1, 2, 3]]  # => [11, 12, 13]
+[x for x in [3, 4, 5, 6, 7] if x > 5] # => [6, 7]
 
 ####################################################
 ## 5. Types
@@ -508,11 +561,11 @@ filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
 # Julia has a type system.
 # Every value has a type; variables do not have types themselves.
 # You can use the `typeof` function to get the type of a value.
-typeof(5) # => Int64
+typeof(5)  # => Int64
 
 # Types are first-class values
-typeof(Int64) # => DataType
-typeof(DataType) # => DataType
+typeof(Int64)     # => DataType
+typeof(DataType)  # => DataType
 # DataType is the type that represents types, including itself.
 
 # Types are used for documentation, optimizations, and dispatch.
@@ -520,80 +573,76 @@ typeof(DataType) # => DataType
 
 # Users can define types
 # They are like records or structs in other languages.
-# New types are defined using the `type` keyword.
+# New types are defined using the `struct` keyword.
 
-# type Name
+# struct Name
 #   field::OptionalType
 #   ...
 # end
-type Tiger
-  taillength::Float64
-  coatcolor # not including a type annotation is the same as `::Any`
+struct Tiger
+    taillength::Float64
+    coatcolor  # not including a type annotation is the same as `::Any`
 end
 
 # The default constructor's arguments are the properties
 # of the type, in the order they are listed in the definition
-tigger = Tiger(3.5,"orange") # => Tiger(3.5,"orange")
+tigger = Tiger(3.5, "orange")  # => Tiger(3.5,"orange")
 
 # The type doubles as the constructor function for values of that type
-sherekhan = typeof(tigger)(5.6,"fire") # => Tiger(5.6,"fire")
+sherekhan = typeof(tigger)(5.6, "fire")  # => Tiger(5.6,"fire")
 
 # These struct-style types are called concrete types
 # They can be instantiated, but cannot have subtypes.
 # The other kind of types is abstract types.
 
 # abstract Name
-abstract Cat # just a name and point in the type hierarchy
+abstract type Cat end  # just a name and point in the type hierarchy
 
 # Abstract types cannot be instantiated, but can have subtypes.
 # For example, Number is an abstract type
-subtypes(Number) # => 2-element Array{Any,1}:
-                 #     Complex{T<:Real}
-                 #     Real
-subtypes(Cat) # => 0-element Array{Any,1}
+subtypes(Number)  # => 2-element Array{Any,1}:
+                  # =>  Complex
+                  # =>  Real
+subtypes(Cat)  # => 0-element Array{Any,1}
 
 # AbstractString, as the name implies, is also an abstract type
-subtypes(AbstractString)    # 8-element Array{Any,1}:
-                            #  Base.SubstitutionString{T<:AbstractString}
-                            #  DirectIndexString
-                            #  RepString
-                            #  RevString{T<:AbstractString}
-                            #  RopeString
-                            #  SubString{T<:AbstractString}
-                            #  UTF16String
-                            #  UTF8String
-
-# Every type has a super type; use the `super` function to get it.
+subtypes(AbstractString)  # => 4-element Array{Any,1}:
+                          # =>  String
+                          # =>  SubString
+                          # =>  SubstitutionString
+                          # =>  Test.GenericString
+
+# Every type has a super type; use the `supertype` function to get it.
 typeof(5) # => Int64
-super(Int64) # => Signed
-super(Signed) # => Integer
-super(Integer) # => Real
-super(Real) # => Number
-super(Number) # => Any
-super(super(Signed)) # => Real
-super(Any) # => Any
+supertype(Int64)    # => Signed
+supertype(Signed)   # => Integer
+supertype(Integer)  # => Real
+supertype(Real)     # => Number
+supertype(Number)   # => Any
+supertype(supertype(Signed))  # => Real
+supertype(Any)      # => Any
 # All of these type, except for Int64, are abstract.
-typeof("fire") # => ASCIIString
-super(ASCIIString) # => DirectIndexString
-super(DirectIndexString) # => AbstractString
-# Likewise here with ASCIIString
+typeof("fire")      # => String
+supertype(String)   # => AbstractString
+# Likewise here with String
+supertype(SubString)  # => AbstractString
 
 # <: is the subtyping operator
-type Lion <: Cat # Lion is a subtype of Cat
-  mane_color
-  roar::AbstractString
+struct Lion <: Cat  # Lion is a subtype of Cat
+    maneColor
+    roar::AbstractString
 end
 
 # You can define more constructors for your type
 # Just define a function of the same name as the type
 # and call an existing constructor to get a value of the correct type
-Lion(roar::AbstractString) = Lion("green",roar)
+Lion(roar::AbstractString) = Lion("green", roar)
 # This is an outer constructor because it's outside the type definition
 
-type Panther <: Cat # Panther is also a subtype of Cat
-  eye_color
-  Panther() = new("green")
-  # Panthers will only have this constructor, and no default constructor.
+struct Panther <: Cat  # Panther is also a subtype of Cat
+    eyeColor
+    Panther() = new("green")
+    # Panthers will only have this constructor, and no default constructor.
 end
 # Using inner constructors, like Panther does, gives you control
 # over how values of the type can be created.
@@ -611,35 +660,36 @@ end
 
 # Definitions for Lion, Panther, Tiger
 function meow(animal::Lion)
-  animal.roar # access type properties using dot notation
+    animal.roar  # access type properties using dot notation
 end
 
 function meow(animal::Panther)
-  "grrr"
+    "grrr"
 end
 
 function meow(animal::Tiger)
-  "rawwwr"
+    "rawwwr"
 end
 
 # Testing the meow function
-meow(tigger) # => "rawwr"
-meow(Lion("brown","ROAAR")) # => "ROAAR"
+meow(tigger)  # => "rawwwr"
+meow(Lion("brown", "ROAAR"))  # => "ROAAR"
 meow(Panther()) # => "grrr"
 
 # Review the local type hierarchy
-issubtype(Tiger,Cat) # => false
-issubtype(Lion,Cat) # => true
-issubtype(Panther,Cat) # => true
+Tiger   <: Cat  # => false
+Lion    <: Cat  # => true
+Panther <: Cat  # => true
 
 # Defining a function that takes Cats
 function pet_cat(cat::Cat)
-  println("The cat says $(meow(cat))")
+    println("The cat says $(meow(cat))")
 end
+# => pet_cat (generic function with 1 method)
 
-pet_cat(Lion("42")) # => prints "The cat says 42"
+pet_cat(Lion("42")) # => The cat says 42
 try
-    pet_cat(tigger) # => ERROR: no method pet_cat(Tiger,)
+    pet_cat(tigger) # => ERROR: MethodError: no method matching pet_cat(::Tiger)
 catch e
     println(e)
 end
@@ -649,130 +699,179 @@ end
 # In Julia, all of the argument types contribute to selecting the best method.
 
 # Let's define a function with more arguments, so we can see the difference
-function fight(t::Tiger,c::Cat)
-  println("The $(t.coatcolor) tiger wins!")
+function fight(t::Tiger, c::Cat)
+    println("The $(t.coatcolor) tiger wins!")
 end
 # => fight (generic function with 1 method)
 
-fight(tigger,Panther()) # => prints The orange tiger wins!
-fight(tigger,Lion("ROAR")) # => prints The orange tiger wins!
+fight(tigger, Panther())  # => The orange tiger wins!
+fight(tigger, Lion("ROAR")) # => The orange tiger wins!
 
 # Let's change the behavior when the Cat is specifically a Lion
-fight(t::Tiger,l::Lion) = println("The $(l.mane_color)-maned lion wins!")
+fight(t::Tiger, l::Lion) = println("The $(l.maneColor)-maned lion wins!")
 # => fight (generic function with 2 methods)
 
-fight(tigger,Panther()) # => prints The orange tiger wins!
-fight(tigger,Lion("ROAR")) # => prints The green-maned lion wins!
+fight(tigger, Panther())  # => The orange tiger wins!
+fight(tigger, Lion("ROAR")) # => The green-maned lion wins!
 
 # We don't need a Tiger in order to fight
-fight(l::Lion,c::Cat) = println("The victorious cat says $(meow(c))")
+fight(l::Lion, c::Cat) = println("The victorious cat says $(meow(c))")
 # => fight (generic function with 3 methods)
 
-fight(Lion("balooga!"),Panther()) # => prints The victorious cat says grrr
+fight(Lion("balooga!"), Panther())  # => The victorious cat says grrr
 try
-  fight(Panther(),Lion("RAWR")) # => ERROR: no method fight(Panther,Lion)
-catch
+    fight(Panther(), Lion("RAWR"))  
+    # => ERROR: MethodError: no method matching fight(::Panther, ::Lion)
+    # => Closest candidates are:
+    # =>   fight(::Tiger, ::Lion) at ...
+    # =>   fight(::Tiger, ::Cat) at ...
+    # =>   fight(::Lion, ::Cat) at ...
+    # => ...
+catch e
+    println(e)
 end
 
 # Also let the cat go first
-fight(c::Cat,l::Lion) = println("The cat beats the Lion")
-# => Warning: New definition
-#    fight(Cat,Lion) at none:1
-# is ambiguous with
-#    fight(Lion,Cat) at none:2.
-# Make sure
-#    fight(Lion,Lion)
-# is defined first.
-#fight (generic function with 4 methods)
+fight(c::Cat, l::Lion) = println("The cat beats the Lion")
+# => fight (generic function with 4 methods)
 
 # This warning is because it's unclear which fight will be called in:
-fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The victorious cat says rarrr
+try
+    fight(Lion("RAR"), Lion("brown", "rarrr"))
+    # => ERROR: MethodError: fight(::Lion, ::Lion) is ambiguous. Candidates:
+    # =>   fight(c::Cat, l::Lion) in Main at ...
+    # =>   fight(l::Lion, c::Cat) in Main at ...
+    # => Possible fix, define
+    # =>   fight(::Lion, ::Lion)
+    # => ...
+catch e
+    println(e)
+end
 # The result may be different in other versions of Julia
 
-fight(l::Lion,l2::Lion) = println("The lions come to a tie")
-fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The lions come to a tie
+fight(l::Lion, l2::Lion) = println("The lions come to a tie") 
+# => fight (generic function with 5 methods)
+fight(Lion("RAR"), Lion("brown", "rarrr"))  # => The lions come to a tie
 
 
 # Under the hood
 # You can take a look at the llvm  and the assembly code generated.
 
-square_area(l) = l * l      # square_area (generic function with 1 method)
+square_area(l) = l * l  # square_area (generic function with 1 method)
 
-square_area(5) #25
+square_area(5)  # => 25
 
 # What happens when we feed square_area an integer?
-code_native(square_area, (Int32,))
-	#	    .section    __TEXT,__text,regular,pure_instructions
-	#	Filename: none
-	#	Source line: 1              # Prologue
-	#	    push    RBP
-	#	    mov RBP, RSP
-	#	Source line: 1
-	#	    movsxd  RAX, EDI        # Fetch l from memory?
-	#	    imul    RAX, RAX        # Square l and store the result in RAX
-	#	    pop RBP                 # Restore old base pointer
-	#	    ret                     # Result will still be in RAX
-
-code_native(square_area, (Float32,))
-	#	    .section    __TEXT,__text,regular,pure_instructions
-	#	Filename: none
-	#	Source line: 1
-	#	    push    RBP
-	#	    mov RBP, RSP
-	#	Source line: 1
-	#	    vmulss  XMM0, XMM0, XMM0  # Scalar single precision multiply (AVX)
-	#	    pop RBP
-	#	    ret
-
-code_native(square_area, (Float64,))
-	#	    .section    __TEXT,__text,regular,pure_instructions
-	#	Filename: none
-	#	Source line: 1
-	#	    push    RBP
-	#	    mov RBP, RSP
-	#	Source line: 1
-	#	    vmulsd  XMM0, XMM0, XMM0 # Scalar double precision multiply (AVX)
-	#	    pop RBP
-	#	    ret
-	#
+code_native(square_area, (Int32,), syntax = :intel)
+	#         .text
+	# ; Function square_area {
+	# ; Location: REPL[116]:1       # Prologue
+	#         push    rbp
+	#         mov     rbp, rsp
+	# ; Function *; {
+	# ; Location: int.jl:54
+	#         imul    ecx, ecx      # Square l and store the result in ECX
+	# ;}
+	#         mov     eax, ecx
+	#         pop     rbp           # Restore old base pointer
+	#         ret                   # Result will still be in EAX
+	#         nop     dword ptr [rax + rax]
+	# ;}
+
+code_native(square_area, (Float32,), syntax = :intel)
+    #         .text
+    # ; Function square_area {
+    # ; Location: REPL[116]:1
+    #         push    rbp
+    #         mov     rbp, rsp
+    # ; Function *; {
+    # ; Location: float.jl:398
+    #         vmulss  xmm0, xmm0, xmm0  # Scalar single precision multiply (AVX)
+    # ;}
+    #         pop     rbp
+    #         ret
+    #         nop     word ptr [rax + rax]
+    # ;}
+
+code_native(square_area, (Float64,), syntax = :intel)
+    #         .text
+    # ; Function square_area {
+    # ; Location: REPL[116]:1
+    #         push    rbp
+    #         mov     rbp, rsp
+    # ; Function *; {
+    # ; Location: float.jl:399
+    #         vmulsd  xmm0, xmm0, xmm0  # Scalar double precision multiply (AVX)
+    # ;}
+    #         pop     rbp
+    #         ret
+    #         nop     word ptr [rax + rax]
+    # ;}
+
 # Note that julia will use floating point instructions if any of the
 # arguments are floats.
 # Let's calculate the area of a circle
 circle_area(r) = pi * r * r     # circle_area (generic function with 1 method)
-circle_area(5)                  # 78.53981633974483
-
-code_native(circle_area, (Int32,))
-	#	    .section    __TEXT,__text,regular,pure_instructions
-	#	Filename: none
-	#	Source line: 1
-	#	    push    RBP
-	#	    mov RBP, RSP
-	#	Source line: 1
-	#	    vcvtsi2sd   XMM0, XMM0, EDI          # Load integer (r) from memory
-	#	    movabs  RAX, 4593140240              # Load pi
-	#	    vmulsd  XMM1, XMM0, QWORD PTR [RAX]  # pi * r
-	#	    vmulsd  XMM0, XMM0, XMM1             # (pi * r) * r
-	#	    pop RBP
-	#	    ret
-	#
-
-code_native(circle_area, (Float64,))
-	#	    .section    __TEXT,__text,regular,pure_instructions
-	#	Filename: none
-	#	Source line: 1
-	#	    push    RBP
-	#	    mov RBP, RSP
-	#	    movabs  RAX, 4593140496
-	#	Source line: 1
-	#	    vmulsd  XMM1, XMM0, QWORD PTR [RAX]
-	#	    vmulsd  XMM0, XMM1, XMM0
-	#	    pop RBP
-	#	    ret
-	#
+circle_area(5)  # 78.53981633974483
+
+code_native(circle_area, (Int32,), syntax = :intel)
+    #         .text
+    # ; Function circle_area {
+    # ; Location: REPL[121]:1
+    #         push    rbp
+    #         mov     rbp, rsp
+    # ; Function *; {
+    # ; Location: operators.jl:502
+    # ; Function *; {
+    # ; Location: promotion.jl:314
+    # ; Function promote; {
+    # ; Location: promotion.jl:284
+    # ; Function _promote; {
+    # ; Location: promotion.jl:261
+    # ; Function convert; {
+    # ; Location: number.jl:7
+    # ; Function Type; {
+    # ; Location: float.jl:60
+    #         vcvtsi2sd       xmm0, xmm0, ecx     # Load integer (r) from memory
+    #         movabs  rax, 497710928              # Load pi
+    # ;}}}}}
+    # ; Function *; {
+    # ; Location: float.jl:399
+    #         vmulsd  xmm1, xmm0, qword ptr [rax] # pi * r
+    #         vmulsd  xmm0, xmm1, xmm0            # (pi * r) * r
+    # ;}}
+    #         pop     rbp
+    #         ret
+    #         nop     dword ptr [rax]
+    # ;}
+
+code_native(circle_area, (Float64,), syntax = :intel)
+    #         .text
+    # ; Function circle_area {
+    # ; Location: REPL[121]:1
+    #         push    rbp
+    #         mov     rbp, rsp
+    #         movabs  rax, 497711048
+    # ; Function *; {
+    # ; Location: operators.jl:502
+    # ; Function *; {
+    # ; Location: promotion.jl:314
+    # ; Function *; {
+    # ; Location: float.jl:399
+    #         vmulsd  xmm1, xmm0, qword ptr [rax]
+    # ;}}}
+    # ; Function *; {
+    # ; Location: float.jl:399
+    #         vmulsd  xmm0, xmm1, xmm0
+    # ;}
+    #         pop     rbp
+    #         ret
+    #         nop     dword ptr [rax + rax]
+    # ;}
 ```
 
 ## Further Reading
 
-You can get a lot more detail from [The Julia Manual](http://docs.julialang.org/en/latest/manual/)
+You can get a lot more detail from the [Julia Documentation](https://docs.julialang.org/)
 
-The best place to get help with Julia is the (very friendly) [mailing list](https://groups.google.com/forum/#!forum/julia-users).
+The best place to get help with Julia is the (very friendly) [Discourse forum](https://discourse.julialang.org/).