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Rico Sta. Cruz 2016-06-02 17:39:31 +08:00
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elixir.md
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@ -32,6 +32,7 @@ is_reference/1
left != right # equal left != right # equal
left !== right # match left !== right # match
left ++ right # concat lists left ++ right # concat lists
left <> right # concat string/binary
left =~ right # regexp left =~ right # regexp
``` ```
@ -76,20 +77,142 @@ Map.put(map, key, value)
### String ### String
```elixir ```elixir
String.length(str) import String
String.codepoints(string) str = "hello"
String.slice(str, 0..-1) str |> length() #=> 5
String.split(str, " ") str |> codepoints() #=> ["h", "e", "l", "l", "o"]
String.capitalize(str) str |> slice(2..-1) #=> "llo"
String.match(string, regex) str |> split(" ") #=> ["hello"]
str |> capitalize() #=> "Hello"
str |> match(regex)
```
### Float
```elixir
import Float
n = 10.3
n |> ceil() #=> 11.0
n |> ceil(2) #=> 11.30
n |> to_string() #=> "1.030000+e01"
n |> to_string([decimals: 2, compact: true])
Float.parse("34") #=> { 34.0, "" }
```
### Integer
```elixir
import Integer
n = 12
digits(n) #=> [1, 2]
to_char_list(n) #=> '12'
to_string(n)
is_even(n)
is_odd(n)
# Different base:
digits(n, 2) #=> [1, 1, 0, 0]
to_char_list(n, 2) #=> '1100'
to_string(n, 2)
parse("12") #=> 12
undigits([1, 2]) #=> 12
```
### Type casting
```elixir
Float.parse("34.1") #=> {34.1, ""}
Integer.parse("34") #=> {34, ""}
Float.to_string(34.1) #=> "3.4100e+01"
Float.to_string(34.1, [decimals: 2, compact: true]) #=> "34.1"
```
### Map
```js
import Map
map = %{id: 1, name: "hi"}
delete(map, :name) #=> "hi"
pop(map, :name) #=> %{id: 1}
put(map, :id, 2) #=> %{id: 2, name: "hi"}
put_new(map, :id, 2) # only if `id` doesn't exist
get(map, :id) #=> 1
keys(map) #=> [:id, :name]
values(map) #=> [1, "hi"]
to_list(map) #=> [id: 1, name: "hi"]
#=> [{:id, 1}, {:name, "hi"}]
merge(map, %{name: "hello"})
Map.new([{:b, 1}, {:a, 2}])
Map.new([a: 1, b: 2])
Map.new([:a, :b], fn x -> {x, x} end) #=> %{a: :a, b: :b}
```
### List
Also see [Enum](#enum).
```js
import List
list = [ 1, 2, 3, 4 ]
first(list)
last(list)
flatten(list)
flatten(list, tail)
``` ```
### Enum ### Enum
```elixir ```elixir
Enum.reduce(list, acc, fn)
Enum.map(list, fn)
# consider streams instead # consider streams instead
import Enum
# High-order
reduce(list, acc, fn)
map(list, fn)
reject(list, fn)
any?(list, fn)
empty?(list, fn)
list = [:a, :b, :c]
at(list, 0) #=> :a
count(list) #=> 3
empty?(list) #=> false
any?(list) #=> true
concat(list, [:d]) #=> [:d]
``` ```
There's really way too many things, just see <https://learnxinyminutes.com/docs/elixir/>. There's really way too many things, just see <https://learnxinyminutes.com/docs/elixir/>.
## Syntax
### [Structs](http://elixir-lang.org/getting-started/structs.html)
```elixir
defmodule User do
defstruct name: "", age: nil
end
%User{name: "John", age: 20}
```
### Functions
### Function heads
```elixir
def join(a, b \\ nil)
def join(a, b) when is_nil(b) do: a end
def join(a, b) do: a <> b; end
```

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---
title: Phoenix: Migrations
category: Elixir
---
## Creating
```
$ mix ecto.gen.migration add_posts_table
creating priv/repo/migrations/20160602085927_add_posts_table.exs
...
$ mix ecto.migrate
$ mix ecto.rollback
```
## Tables
```elixir
create table(:documents) do
add :title, :string
add :title, :string, size: 40
add :title, :string, default: "Hello"
add :title, :string, default: fragment("now()")
add :title, :string, null: false
add :body, :text
add :age, :integer
add :price, :float
add :price, :float, precision: 10, scale: 2
add :published_at, :datetime
add :group_id, references(:groups)
add :object, :json
timestamps # inserted_at and updated_at
end
create_if_not_exists table(:documents) do: ... end
```
```elixir
alter table(:posts) do
add :summary, :text
modify :title, :text
remove :views
end
```
```elixir
rename table(:posts), :title, to: :summary
rename table(:posts), to: table(:new_posts)
```
```elixir
drop table(:documents)
drop_if_exists table(:documents)
table(:documents)
table(:weather, prefix: :north_america)
```
## Indices
```elixir
create index(:posts, [:slug], concurrently: true)
create unique_index(:posts, [:slug])
drop index(:posts, [:name])
```
## Execute
```elixir
execute "UPDATE posts SET published_at = NULL"
execute create: "posts", capped: true, size: 1024
```
## References
* [Ecto.Migration](http://devdocs.io/phoenix/ecto/ecto.migration)

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---
title: Phoenix
category: Elixir
---
### Directory
```
config/
web/
controllers/
models/
views/
templates/
static/
```
## Migrations
```
$ mix ecto.gen.migration add_posts_table
creating priv/repo/migrations/20160602085927_add_posts_table.exs
...
$ mix ecto.migrate
```
### [Ecto.Migration](http://devdocs.io/phoenix/ecto/ecto.migration)
```
create index(:posts, [:slug], concurrently: true)
create table(:documents) do
add :body, :string
add :deletion_key, :string
timestamps
end
```