Why another FSM implementation? Because we didn't see one suited for smaller-scale, programmatic use in Go which was very efficient. Example use:
bp := fsm.New()
bp.Start(0)
bp.From(0).To(1)
bp.From(1).To(2).Then(func (m *fsm.Machine) { fmt.Println("hola!") })
m := bp.Machine()
m.State() // => a
m.Goto(1) // => error(nil)
m.State() // => b
m.Goto(2) // => error(nil)
// => hola!
m.Goto(1) // => error, "Transition 2 to 1 not permitted."See the godocs for more information.
Benchmarks well, especially against comparable solutions.
➜ fsm git:(fsm) ✗ go test -bench=.
PASS
PASS
BenchmarkTransitions 100000000 20.8 ns/op
BenchmarkAllows 50000000 20.6 ns/op
BenchmarkGetState 2000000000 0.48 ns/op