These are tables of example machines.

If a cell is marked with a star ⭐, it is considered the preferred machine for that specific example. So, you can see from the star on "edge kinds" that Traffic light is the preferred machine for that example, in Useful Machines.

If a machine has a coffee cup ☕, that machine uses that feature.

Useful Machines

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Light switch

Pretty obvious two-stater. Starts in Off; switches back and forth on toggle.

Off 'toggle' <=> 'toggle' On;

Traffic light

Pretty obvious two-stater. Starts in Off; turns on with enable; when on, cycles on next, or back to Off with disable. Does not offer enable or disable when not appropriate.

Off 'enable' -> Red;
Red 'next' => Green 'next' => Yellow 'next' => Red;
[Red Yellow Green] 'disable' ~> Off;

Traffic intersection

Offers six states - red yellow green for north, and the same for east. Shows red in the unnamed direction. Guarantees four-light sync at all times.

Off 'enable' -> GreenNorth;

GreenNorth 'next' => YellowNorth 'next' => RedNorth 'next' =>
GreenEast 'next'  => YellowEast  'next' => RedEast  'next' =>
GreenNorth;

[GreenNorth YellowNorth RedNorth GreenEast YellowEast RedEast] 'disable' ~> Off;

TCP/IP

TCP/IP, essentially the foundation of the internet, is fundamentally defined as a state machine and currently codified on page 22 of RFC793.

A TCP/IP socket both starts and ends in Closed.

Closed 'Passive open'      -> Listen;
Closed 'Active Open / SYN' -> SynSent;

Listen 'Close'         -> Closed;
Listen 'Send / SYN'    -> SynSent;
Listen 'SYN / SYN+ACK' -> SynRcvd;

SynSent 'Close'         -> Closed;
SynSent 'SYN / SYN+ACK' -> SynRcvd;
SynSent 'SYN+ACK / ACK' -> Established;

SynRcvd 'Timeout / RST' -> Closed;
SynRcvd 'Close / FIN'   -> FinWait1;
SynRcvd 'ACK'           -> Established;

Established 'Close / FIN' -> FinWait1;
Established 'FIN / ACK'   -> CloseWait;

FinWait1 'FIN / ACK'     -> Closing;
FinWait1 'FIN+ACK / ACK' -> TimeWait;
FinWait1 'ACK / Nothing' -> FinWait2;

FinWait2  'FIN / ACK'   -> TimeWait;
Closing   'ACK'         -> TimeWait;
TimeWait  'Up to 2*MSL' -> Closed;
CloseWait 'Close / FIN' -> LastAck;

LastAck 'ACK' -> Closed;

If you want to play golf, you can get that down to seven lines using lists and chaining:

Closed 'Passive open' -> Listen 'Send / SYN' -> SynSent;
[Listen SynSent] 'Close' -> Closed 'Active Open / SYN' -> SynSent 'SYN+ACK / ACK' -> Established 'FIN / ACK' -> CloseWait 'Close / FIN' -> LastAck 'ACK' -> Closed;
[SynRcvd Established] 'Close / FIN' -> FinWait1 'FIN / ACK' -> Closing 'ACK' -> TimeWait
[Listen SynSent] 'SYN / SYN+ACK' -> SynRcvd 'Timeout / RST' -> Closed;
FinWait1 'FIN+ACK / ACK' -> TimeWait 'Up to 2*MSL' -> Closed;
FinWait1 'ACK / Nothing' -> FinWait2 'FIN / ACK' -> TimeWait;
SynRcvd 'ACK' -> Established;

Comedy Machines

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