diff options
Diffstat (limited to 'elixir.html.markdown')
| -rw-r--r-- | elixir.html.markdown | 53 |
1 files changed, 37 insertions, 16 deletions
diff --git a/elixir.html.markdown b/elixir.html.markdown index 946c0a1b..720e080c 100644 --- a/elixir.html.markdown +++ b/elixir.html.markdown @@ -2,6 +2,7 @@ language: elixir contributors: - ["Joao Marques", "http://github.com/mrshankly"] + - ["Dzianis Dashkevich", "https://github.com/dskecse"] filename: learnelixir.ex --- @@ -59,7 +60,7 @@ tail #=> [2,3] # the tuples have different sizes. # {a, b, c} = {1, 2} #=> ** (MatchError) no match of right hand side value: {1,2} -# There's also binaries +# There are also binaries <<1,2,3>> # binary # Strings and char lists @@ -90,6 +91,11 @@ string. <<1,2,3>> <> <<4,5>> #=> <<1,2,3,4,5>> "hello " <> "world" #=> "hello world" +# Ranges are represented as `start..end` (both inclusive) +1..10 #=> 1..10 +lower..upper = 1..10 # Can use pattern matching on ranges as well +[lower, upper] #=> [1, 10] + ## --------------------------- ## -- Operators ## --------------------------- @@ -108,7 +114,7 @@ div(10, 2) #=> 5 # To get the division remainder use `rem` rem(10, 3) #=> 1 -# There's also boolean operators: `or`, `and` and `not`. +# There are also boolean operators: `or`, `and` and `not`. # These operators expect a boolean as their first argument. true and true #=> true false or true #=> true @@ -119,7 +125,6 @@ false or true #=> true 1 || true #=> 1 false && 1 #=> false nil && 20 #=> nil - !true #=> false # For comparisons we have: `==`, `!=`, `===`, `!==`, `<=`, `>=`, `<` and `>` @@ -165,12 +170,12 @@ case {:one, :two} do {:four, :five} -> "This won't match" {:one, x} -> - "This will match and assign `x` to `:two`" + "This will match and bind `x` to `:two`" _ -> "This will match any value" end -# It's common practice to assign a value to `_` if we don't need it. +# It's common to bind the value to `_` if we don't need it. # For example, if only the head of a list matters to us: [head | _] = [1,2,3] head #=> 1 @@ -190,7 +195,7 @@ cond do "But I will" end -# It is common to see a last condition equal to `true`, which will always match. +# It is common to set the last condition equal to `true`, which will always match. cond do 1 + 1 == 3 -> "I will never be seen" @@ -301,7 +306,7 @@ end Recursion.sum_list([1,2,3], 0) #=> 6 # Elixir modules support attributes, there are built-in attributes and you -# may also add custom attributes. +# may also add custom ones. defmodule MyMod do @moduledoc """ This is a built-in attribute on a example module. @@ -312,21 +317,24 @@ defmodule MyMod do end ## --------------------------- -## -- Records and Exceptions +## -- Structs and Exceptions ## --------------------------- -# Records are basically structures that allow you to associate a name with -# a particular value. -defrecord Person, name: nil, age: 0, height: 0 +# Structs are extensions on top of maps that bring default values, +# compile-time guarantees and polymorphism into Elixir. +defmodule Person do + defstruct name: nil, age: 0, height: 0 +end -joe_info = Person.new(name: "Joe", age: 30, height: 180) -#=> Person[name: "Joe", age: 30, height: 180] +joe_info = %Person{ name: "Joe", age: 30, height: 180 } +#=> %Person{age: 30, height: 180, name: "Joe"} # Access the value of name joe_info.name #=> "Joe" # Update the value of age -joe_info = joe_info.age(31) #=> Person[name: "Joe", age: 31, height: 180] +older_joe_info = %{ joe_info | age: 31 } +#=> %Person{age: 31, height: 180, name: "Joe"} # The `try` block with the `rescue` keyword is used to handle exceptions try do @@ -335,6 +343,7 @@ rescue RuntimeError -> "rescued a runtime error" _error -> "this will rescue any error" end +#=> "rescued a runtime error" # All exceptions have a message try do @@ -343,6 +352,7 @@ rescue x in [RuntimeError] -> x.message end +#=> "some error" ## --------------------------- ## -- Concurrency @@ -360,7 +370,14 @@ spawn(f) #=> #PID<0.40.0> # `spawn` returns a pid (process identifier), you can use this pid to send # messages to the process. To do message passing we use the `send` operator. # For all of this to be useful we need to be able to receive messages. This is -# achived with the `receive` mechanism: +# achieved with the `receive` mechanism: + +# The `receive do` block is used to listen for messages and process +# them when they are received. A `receive do` block will only +# process one received message. In order to process multiple +# messages, a function with a `receive do` block must recursively +# call itself to get into the `receive do` block again. + defmodule Geometry do def area_loop do receive do @@ -376,6 +393,8 @@ end # Compile the module and create a process that evaluates `area_loop` in the shell pid = spawn(fn -> Geometry.area_loop() end) #=> #PID<0.40.0> +# Alternatively +pid = spawn(Geometry, :area_loop, []) # Send a message to `pid` that will match a pattern in the receive statement send pid, {:rectangle, 2, 3} @@ -394,5 +413,7 @@ self() #=> #PID<0.27.0> * [Getting started guide](http://elixir-lang.org/getting_started/1.html) from [elixir webpage](http://elixir-lang.org) * [Elixir Documentation](http://elixir-lang.org/docs/master/) +* ["Programming Elixir"](https://pragprog.com/book/elixir/programming-elixir) by Dave Thomas +* [Elixir Cheat Sheet](http://media.pragprog.com/titles/elixir/ElixirCheat.pdf) * ["Learn You Some Erlang for Great Good!"](http://learnyousomeerlang.com/) by Fred Hebert -* "Programming Erlang: Software for a Concurrent World" by Joe Armstrong +* ["Programming Erlang: Software for a Concurrent World"](https://pragprog.com/book/jaerlang2/programming-erlang) by Joe Armstrong |