Learn Elixir in One Video
In this tutorial I will cover the core syntax of the Elixir language in one video. If you jump to YouTube you’ll find time stamps so you can easily jump to what interests you. You can also use the time stamps so you can watch this video in parts.
I cover Input / Output, Data Types, Strings, Math, Comparison, Decision Making, Tuples, Lists, Maps, Pattern Matching, Anonymous Functions, Recursion, Looping, Enumerables, List Comprehensions, Exception Handling, Concurrency and more.
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Code & Cheat Sheet
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# This creates your module which holds all your # functions defmodule M do # Functions start with def, the functions name # and then end def main do # gets retrieves user input # trim removes the newline name = IO.gets("What is your name? ") |> String.trim # You can combine string and variable output # with #{} IO.puts "Hello #{name}" data_stuff() end # ----- DATA TYPES ----- # Variables start with lowercase letters or # underscores and then uppercase letters, # underscores or numbers # Once set a variables value can't change # Types Integers, Floats, Atoms, Ranges, # Binaries, Lists, Maps, Tuples def data_stuff do # There is no maximum int size my_int = 123 IO.puts "Integer #{is_integer(my_int)}" # Floats have about 16 digit precision my_float = 3.14159 IO.puts "Float #{is_float(my_float)}" # An Atoms name is its value IO.puts "Atom #{is_atom(:Pittsburgh)}" # Use double quotes for spaces :"New York" # Ranges define a start and end using ints one_to_10 = 1..10 # ----- STRINGS ----- # Strings are defined with double quotes my_str = "My Sentence" IO.puts "Length : #{String.length(my_str)}" # You can combine strings longer_str = my_str <> " " <> "is longer" # Compare strings IO.puts "Equal : #{"Egg" === "egg"}" # Check if a string contains a string IO.puts "My ? #{String.contains?(my_str, "My")}" # Return first character IO.puts "First : #{String.first(my_str)}" # Get character at index IO.puts "Index 4 : #{String.at(my_str, 4)}" # Get a substring IO.puts "Substring : #{String.slice(my_str, 3, 8)}" # Split a string into a list # Inspect which prints the internal # representation of a value IO.inspect String.split(longer_str, " ") # Reverse a string IO.puts String.reverse(longer_str) # Uppercase IO.puts String.upcase(longer_str) # Lowercase IO.puts String.downcase(longer_str) # Capitalize IO.puts String.capitalize(longer_str) # Pipe output from one to another 4 * 10 |> IO.puts # ----- MATH ----- IO.puts "5 + 4 = #{5+4}" IO.puts "5 - 4 = #{5-4}" IO.puts "5 * 4 = #{5*4}" IO.puts "5 / 4 = #{5/4}" IO.puts "5 div 4 = #{div(5,4)}" IO.puts "5 rem 4 = #{rem(5,4)}" # ----- COMPARISON ----- IO.puts "4 == 4.0 : #{4 == 4.0}" # Checks for equality of value and type IO.puts "4 === 4.0 : #{4 === 4.0}" IO.puts "4 != 4.0 : #{4 != 4.0}" # Checks for inequality of value and type IO.puts "4 !== 4.0 : #{4 == 4.0}" IO.puts "5 > 4 : #{5 > 4}" IO.puts "5 >= 4 : #{5 >= 4}" IO.puts "5 < 4 : #{5 < 4}" IO.puts "5 <= 4 : #{5 <= 4}" # Logical operators age = 16 IO.puts "Vote & Drive : #{(age >= 16) and (age >= 18)}" IO.puts "Vote or Drive : #{(age >= 16) or (age >= 18)}" # Converts true to false vice versa IO.puts not true # ----- DECISION MAKING ----- # If and Else if age >= 18 do IO.puts "Can Vote" else IO.puts "Can Wait" end # Unless unless age === 18 do IO.puts "You're not 18" else IO.puts "You're 18" end # Cond works like else if # it only hits the 1st match cond do age >= 14 -> IO.puts "You can wait" age >= 16 -> IO.puts "You can drive" age >= 18 -> IO.puts "You can vote" true -> IO.puts "Default" end # Case works like switch case 2 do 1 -> IO.puts "Entered 1" 2 -> IO.puts "Entered 2" _ -> IO.puts "Default" end # Ternary operator IO.puts "Ternary : #{if age > 18, do: "Can Vote", else: "Can't Vote"}" # ----- TUPLES ----- # Tuples normally have 2 to 4 values # They can hold any value # They aren't for enumerating, or # cycling through like lists # They ar for pattern matching # Create a tuple my_stats = {175, 6.25, :Derek} IO.puts "Tuple #{is_tuple(my_stats)}" # You can append values my_stats2 = Tuple.append(my_stats, 42) # Retrieve values by index IO.puts "Age #{elem(my_stats2, 3)}" # Get tuple size IO.puts "Size #{tuple_size(my_stats2)}" # Delete an index my_stats3 = Tuple.delete_at(my_stats2, 0) # Insert at an index my_stats4 = Tuple.insert_at(my_stats3, 0, 1974) # Create a tuple with the same values # duplicated a number of times many_zeroes = Tuple.duplicate(0, 5) # You can use tuples for pattern matching {weight, height, name} = {175, 6.25, :Derek} IO.puts "Weight : #{weight}" # ----- LISTS ----- # Lists contain lists of data of any data type list1 = [1,2,3] list2 = [4,5,6] # You can combine Lists list3 = list1 ++ list2 # You can subtract Lists list4 = list3 -- list1 # Verify if an item is in a list IO.puts 6 in list4 # Separate the head and tail of list [head | tail] = list3 IO.puts "Head : #{head}" # Write to the screen without a newline IO.write "Tail : " # To show the tail use inspect IO.inspect tail # Inspect which prints the internal # representation of a # value may give odd results IO.inspect [97,98] # You can force inspect to print as a list # like this IO.inspect [97,98], char_lists: :as_lists # Enum can enumerate over lists Enum.each tail, fn item -> IO.puts item end words = ["Random", "Words", "in a", "list"] Enum.each words, fn word -> IO.puts word end # We can use recursion to loop as well display_list(words) # Delete deletes the given item from a list IO.puts display_list(List.delete(words,"Random")) # Delete item at index IO.puts display_list(List.delete_at(words,1)) # Insert item at index IO.puts display_list(List.insert_at(words,4, "Yeah")) # Get first item IO.puts List.first(words) # Get last item IO.puts List.last(words) # You can create lists of key value tuples my_stats5 = [name: "Derek", height: 6.25, weight: 175] # ----- MAPS ----- # Maps hold collections of key value pairs capitals = %{"Alabama" => "Montgomery", "Alaska" => "Juneau", "Arizona" => "Phoenix"} # Retrieve values using the key IO.puts "Capital of Alaska is #{capitals["Alaska"]}" # You can use atoms as keys capitals2 = %{alabama: "Montgomery", alaska: "Juneau", arizona: "Phoenix"} IO.puts "Capital of Arizona is #{capitals2.arizona}" # Insert a key / value capitals3 = Dict.put_new(capitals, "Arkansas", "Big Rock") # ----- PATTERN MATCHING ----- # With pattern matching we can retrieve # data from data structures [length, width] = [20, 30] IO.puts "Width : #{width}" # If you don't care about data use _ [_, [_, a]] = [20, [30, 40]] IO.puts "Get Num : #{a}" # ----- ANONYMOUS FUNCTIONS ----- # An anonymous function has no name and can # be passed to another function get_sum = fn (x, y) -> x + y end IO.puts "5 + 5 = #{get_sum.(5,5)}" # Shorthand of th above # Increment the parameter names by 1 get_less = &(&1 - &2) IO.puts "7 - 6 = #{get_less.(7,6)}" # You can have functions except different # numbers of parameters add_sum = fn {x,y} -> IO.puts "#{x} + #{y} = #{x+y}" {x,y,z} -> IO.puts "#{x} + #{y} + #{z} = #{x+y+z}" end add_sum.({1,2}) add_sum.({1,2,3}) # You can set defaults for parameters IO.puts do_it() # ----- RECURSION ----- # Recursion is the act of a function # calling itself IO.puts "Factorial of 3 : #{factorial(4)}" # ----- LOOPING ----- # With most languages we loop by # incrementing or decrementing a value # Since all variables are immutable # in Elixir we use recursion to loop IO.puts "Sum : #{sum([1,2,3])}" # An Elixir for loop loop(5,1) # ----- ENUMERABLES ----- # An enumerable can have its items # counted off # Check if all values are even IO.puts "Even List : #{Enum.all?([1,2,3], fn(n) -> rem(n,2) == 0 end)}" # Check if any items are even IO.puts "Even Item : #{Enum.any?([1,2,3], fn(n) -> rem(n,2) == 0 end)}" # Print out each item Enum.each([1,2,3], fn(n) -> IO.puts n end) # Double each value in a list dbl_list = Enum.map([1,2,3], fn(n) -> n * 2 end) IO.inspect dbl_list # Reduce down to a single value sum_vals = Enum.reduce([1,2,3], fn(n, sum) -> n + sum end) IO.puts "Sum : #{sum_vals}" IO.inspect Enum.uniq([1,2,2]) # ----- LIST COMPREHENSIONS ----- # Provides an additonal way to perform # actions on a list # Double every list item dbl_list2 = for n <- [1,2,3], do: n * 2 IO.inspect dbl_list2 # Create a list of evens even_list = for n <- [1,2,3,4], rem(n,2) == 0, do: n IO.inspect even_list # ----- EXCEPTION HANDLING ----- # Allows us to handle errors err = try do 5 / 0 rescue ArithmeticError -> "Can't Divide by Zero" end IO.puts err # ----- CONCURRENCY ----- # Running multiple blocks of code at once # Calling spawn starts a new process that # runs the code specified at an undefined # time # Spawn returns a Process ID (PID) spawn(fn() -> loop(50, 1) end) spawn(fn() -> loop(100, 50) end) # We can send messgaes between # processes # Send a message to this process # and receive it send(self(), {:french, "Bob"}) receive do {:german, name} -> IO.puts "Guten tag #{name}" {:french, name} -> IO.puts "Bonjour #{name}" {:english, name} -> IO.puts "Hello #{name}" # If there is no matching message you can issue # a timeout like I did for 500 milliseconds after 500 -> IO.puts "Times up" end end # ----- RECURSIVE FUNCTIONS ----- # Output list with recursion def display_list([word|words]) do IO.puts word display_list(words) end def display_list([]), do: nil # Calculate a factorial def factorial(num) do # This will end the calling of # additional functions if num <= 1 do 1 else result = num * factorial(num - 1) result end end # 1st : result = 4 * factorial(3) = 4 * 6 = 24 # 2nd : result = 3 * factorial(2) = 3 * 2 = 6 # 3rd : result = 2 * factorial(1) = 2 * 1 = 2 # Demonstrate looping # Sum values in a list # Decide what happens if we get an empty list def sum([]), do: 0 # Empty the list as we sum values def sum([h|t]), do: h + sum(t) # A Elixir for loop # What happens if the 1st attribute is 0 def loop(0,_), do: nil def loop(max, min) do if max < min do loop(0, min) else IO.puts "Num : #{max}" loop(max - 1, min) end end # ----- DEFINE DEFAULTS ----- # Define defaults with \\ def do_it(x \\ 1, y \\ 1) do x + y end end |
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