Naming function

Body is a function block

　　Do ... end block is organized way of expression.

# ./times.exs下
defmodule Times do
    def doule(n) do
        n * 2
    end
end

And pattern-matching function calls

　　code show as below:

./ # factorial.exs computing class 
defmodule Factorial do 
    DEF of (0), do: # 1 termination condition to write on it, otherwise it will never be enforced to the 
    DEF of (the n-), do: the n-* of (the n-- 1 )
 End

Sentinel clause

　　code show as below:

defmodule Guard do
    def what_is(x) when is_number(x) do
        IO.puts "#{x} is a number"
    end
    def what_is(x) when is_list(x) do
        IO.puts "#{x} is a list"
    end
    def what_is(x) when is_atom(x) do
        IO.puts "#{x} is an atom"
    end
end

　　They assert immediately after the function is defined by one or more when keywords. When executed, the first execution based on matching parameters, and then evaluate all when assertions.

　　Sentinel clause does not support && and ||

The default parameters

　　When you define a function name, you can use param \\ value statement to specify default values for any parameter.

# ./default_param.exs
defmodule Example do
    def func(p1, p2 \\ 2, p3 \\ 3, p4) do
        IO.inspect [p1, p2, p3, p4]
    end
end

Example.func("a", "b")        #=> ["a", 2, 3, "b"]
Example.func("a", "b", "c")    #=> ["a", "b", 3, "c"]   从从左到右匹配
Example.func("a", "b", "c", "d")

　　There may receive the following error:

FUNC DEF (p1, P2 \\ 2, \\ 3 p3 , P4) 

DEF FUNC (p1, P2) # When the two arguments, calls can not be determined 


DEF FUNC (p1, P2 \\ 123 ) # pass two when the parameters can not be determined call

def func(p1, p2)

　　You can add a parameter contains default, and no function calls on all body functions, while the rest use common functions, those default values will be applied to this function only function header section

Part # omitted 
DEF FUNC (P1, P2 \\ 123 ) 

DEF FUNC (P1, P2) When ... 

DEF FUNC (P1, P2) ...

|> Pipeline operator

　　|> The result left expression, which is passed to the right of the function call as the first parameter

people = DB.find_customers
orders = Orders.for_customers(people)
tax = sales_tax(orders, 2013)
filing = prepare_filing(tax)
#可以写为
filing = DB.find_customers
        |> Orders.for_customers
        |> sales_tax(2013)
        |> prepare_filing

val |> f( a, b ) 等价于 f( val, a, b)

Module

　　Module provides a namespace for content definition. It can be used to encapsulate named functions, macros can also be encapsulated, structure, protocols, and other modules

Command module

　　Its scope in order to appear at the instruction as a starting point, until the end of the current scope

　　import

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