mnesia.exs

defrecord User, name: "", email: ""

defmodule Amnesia do

  @compile {:parse_transform, :qlc}

  def create_schema do
    create_table User
  end

  def find(record, id) do
    :mnesia.read(record, id)
  end

  def write(object) do
    :mnesia.write(object)
  end

  def delete(_user=User[]), do: nil
  def delete(object) do
    :mnesia.delete_object(object)
  end

  def create_table(record) do
    :mnesia.create_table(record, [{:attributes, Dict.keys(record.__record__(:fields))}])
  end
end


:mnesia.start

Amnesia.create_schema

{:atomic, :ok} = :mnesia.transaction fn ->
  Amnesia.write(User.new(name: "John Doe", email: "jdoe@example.com"))
end

{:atomic, user} = :mnesia.transaction fn ->
  Amnesia.find(User, "jdoe@example.com")
end

IO.inspect user

{:atomic, users} = :mnesia.transaction fn ->
  query = :qlc.q(lc u inlist :mnesia.table(User), u.name == "John Doe", do: u)
  :qlc.e(query)
end

IO.inspect users

# $ elixir mnesia.exs
# mnesia.exs:45: warning: qlc:q/1 called, but "qlc.hrl" not included
# []
# ** (MatchError) no match of right hand side value: {:aborted,
# {:function_clause, [{:elixir_compiler_0, :"-__FILE__/1-lc$^0/1-0-",
# [qlc_handle: {:qlc_table, #Function<20.61328436/1 in :mnesia.table/2>, true,
# #Function<21.61328436/1 in :mnesia.table/2>, #Function<22.61328436/0 in
# :mnesia.table/2>, #Function<23.61328436/1 in :mnesia.table/2>,
# #Function<26.61328436/1 in :mnesia.table/2>, #Function<25.61328436/2 in
# :mnesia.table/2>, #Function<24.61328436/0 in :mnesia.table/2>, :"=:=",
# :undefined, :no_match_spec}], [file: 'mnesia.exs', line: 45]},
# {:elixir_compiler_0, :"-__FILE__/1-fun-2-", 0, [file: 'mnesia.exs', line:
# 45]}, {:mnesia_tm, :apply_fun, 3, [file: 'mnesia_tm.erl', line: 833]},
#    {:mnesia_tm, :execute_transaction, 5, [file: 'mnesia_tm.erl', line: 813]},
#    {:elixir_compiler_0, :__FILE__, 1, [file: 'mnesia.exs', line: 44]},
#    {:elixir_compiler, :dispatch_loaded, 6, [file: 'src/elixir_compiler.erl',
#    line: 84]}, {:elixir_lexical, :run, 2, [file: 'src/elixir_lexical.erl',
#    line: 17]}, {:elixir_compiler, :quoted, 2, [file:
#    'src/elixir_compiler.erl', line: 26]}]}}
#        mnesia.exs:44: (file)
#            (elixir) src/elixir_lexical.erl:17: :elixir_lexical.run/2
#                (elixir) lib/code.ex:303: Code.require_file/2