ExFSM

Simple Elixir library to define composable mealy FSM as function (not related at all with :gen_fsm, no state/process management).

defmodule Light do
  use ExFSM

  deftrans on({:off, _}, state), do: {:next_state, :off, state}
  deftrans off({:on, _}, state), do: {:next_state, :on, state}
end

defmodule Light.State do
  @enforced_keys [:state]
  defstruct  @enforced_keys
end

defimpl ExFSM.Machine.State, for: Light.State do
  def state_name(state), do: state.state
  def set_state_name(state, state_name), do: struct(state, state: state_name)
  def handlers(_state), do: [Light]
end

{:next_state, %_{state: :off} = state} = ExFSM.Machine.event({:on, nil},  %Light{state: :off})
{:next_state, %_{state: :on} = state} =  ExFSM.Machine.event({:off, nil}, %Light{state: :on})
{:error, :illegal_action} =              ExFSM.Machine.event({:on, nil},  %Light{state: :on})

• define an FSM with handler modules defining each transition as a simple function but using a macro deftrans which creates a function fsm returning the fsm transition map for this handler module.
• deftrans has the same semantic as erlang in memory FSM gen_fsm
• combine together multiple FSM handlers to create a "meta" FSM.
• send event with the function event which simply find the right handler, execute the handler function.

Usage

See in in code documentation

CONTRIBUTING

Hi, and thank you for wanting to contribute. Please refer to the centralized informations available at: https://github.com/kbrw\#contributing