This repository is a collection of some simple examples of using "plain" Julia
(i.e. not dependent on any particular library) to implement state machines. The
initial Cake and RegEx examples were first covered in the JuliaCon 2019 talk
titled "Julia's Killer App(s): Implementing State Machines Simply using Multiple
Dispatch" (video).
Any suggestions or improvements to the existing examples are welcomed. Additionally, any additional "simple state machine" examples would definitely be considered for inclusion.
Cake is a fun, simple demonstration of encoding the process of baking a cake
as a state machine. Possible states are:
NeedIngredients- initial state; tracks ingredients already gatheredMixBatter- tracks remaining ingredients to be addedRuinedBatterRawBatterBurntCakeTastyCake
Possible transitions are:
Gather- specifies the ingredient being gatheredAdd- specifies the ingredients being added to the batterBake- specifies the temperature the batter is being baked at
Finally, the step function accepts a state and a transition and always returns
a new state. As such, it can be used to reduce over a list of transitions in
order to "run" the state machine.
The RegEx example does not actually encode a full regular language
expression parser, but rather demonstrates the beginnings of how one might be
implemented as a state machine in Julia. In this implementation various
Matchers are used as the states and the characters of the string to be
matched, converted to Val types, are the transitions. Unlike the Cake
example where the state machine had a fixed structure encoded in the
implementation, the Matchers used in RegEx behave as a linked-list or tree
of states. Matchers currently implemented include:
MatchCharWildcardOr