There really isn't that much to it. E.g. in Python you can just use a dict. # (state, event) => (next state, action) FSM = {} Add transitions (using

There really isn't that much to it. E.g. in Python you can just use a dict. # (state, event) => (next state, action) FSM = {} Add transitions (using enums): # Simple left down-[move*]-up sequences. FSM[STATE.clear, EVENT.left_down ] = STATE.set_caret, 'set_insertion_point' FSM[STATE.set_caret, EVENT.left_motion] = STATE.set_caret, 'set_insertion_point' FSM[STATE.set_caret, EVENT.left_up ] = STATE.clear, 'nothing' Then when an event happens you drive the FSM like so: new_state, action = FSM[state, event] Check out https://git.sr.ht/~sforman/Xerblin/tree/trunk/item/xerblin/gui/mousebindings.py https://git.sr.ht/~sforman/Xerblin/tree/trunk/item/xerblin/g... for an example. There is also a DOT file (and SVG image) of the resulting state graph (the code to generate the DOT file directly from the FSM dict is at the bottom of the mousebindings.py file.)