字典：散列表、散列字典、关键字列表、集合与结构体

defmodule Sum do
    def values(dict) do
        dict |> Dict.values |> Enum.sum
    end
end

hd = [ one: 1, two: 2, three: 3 ] |> Enum.into HashDict.new
IO.puts Sum.values(hd)      #=>6

kw_list = [name: "Dave", likes: "Programming", where: "Dallas"]
hashdict = Enum.into kw_list, HashDixt.new
map = Enum.into kw_list, Map.new

kw_list[:name]        #=>"Dave"
hashdict[:likes]        #=>"Programming"
map[:where]        #=>"Dallas"

hashdict = Dict.drop(hashdict, [:where, :likes])        #=>HashDict<[name: "Dave"]>
hashdict = Dict.put(hashdict, :also_likes, "Ruby)        #=>HashDict<[name: "Dave", also_likes: "Ruby"]>
combo = Dict.merge(map, hashdict)        #合并=>%{also_likes: "Ruby", likes: "Programming", name: "Dave", where: "Dallas"}

people = [
    %{ name: "Grumpy, height: 1.24 },
    %{ name: "Dave", height: 1.88 },
    %{ name: "Dopey", height: 1.32 },
    %{ name: "Shaquille", height: 2.16 },
    %{ name: "Sneezy", height: 1.28 }
    ]
for person = %{ height: height } <- people,     #将列表中的散列表绑定到person ，并将高度值绑定到height
    height > 1.5,            #筛选出高度高于1.5的
    do: IO.inspect person    

def book(%{name: name, height: height})
when height > 1.9 do
    ...
end

def book(%{name: name, height: height})
when height < 1.3 do
    ...
end

def book(person) do
    ...
end

people |> Enum.each(&HotelRoom.book/1)

m = %{ a: 1, b: 2, c: 3 }
m1 = %{ m | b: "two", c: "three" }        #%{ a: 1, b: "two, c: "three" }
    #要增加新的键值需要使用Dict.put_new/3函数

defmodule Subscriber do
    defstruct name: "", paid: false, over_18: true
end

s1 = %Subscriber{}        #=>%Subscriber{name: "", over_18: true, paid: false }
s2 = %Subscriber{name: "Mary", paid: true}        #=>%Subscriber{name: "Mary", over_18: true, paid: true }

匹配
s2.name            #通过点标记访问，键必须为原子，符合结构体的特性
%Subscriber{name: a_name} = s3
a_name            #=>"Mary"

更新
s3 = %Subscriber{ s2 | name: "Marie" }

defmodule Attendee do
    defstruct name: "", paid: false, over_18: true

    def may_attend_after_party(attendee = %Attendee{}) do　　　　#函数参数使用 %Attendee{} 接受结构体
        attendee.paid && attendee.over_18
    end

    def print_vip_badge(%Attendee{name: name}) when name != "" do
        IO.puts "Very cheap badge for #{name}"
    end
      
    def print_vip_bage(%Attendee{}) fo
        raise "missing name for badge"
    end
end

defmodule Attendee do
    @derive Access
    defstruct name: "", over_18: false
end

a = %Attendee{name: "Sally", over_18: true}
a[:name]          #=> "Sally

defmodule Customer do
    defstruct name: "", company: ""
end

defmodule BugReport do
    defstruct owner: %{}, details: "", serverity: 1
end


report = %BugReport{owner: %Customer{name: "Dave", company: "Pragmatic"}, detail: "broken"}

#访问
report.owner.company

#更新/修改
report = %BugReport{ report | owner: %Customer{ report.owner | company: "PragProg" }}

#put_in可以设置嵌套结构里面的值
put_in(report.owner.company, "PargProg")

#update_in可以让我们在结构体上的某一个值上执行一个函数
update_in(report.owner.name, &("Mr. " <> &1))    #连接 "Mr. "和name