I think it should be quite nice to write an interpreter in Haskell (and then introduce meta-circular to it?)

e.g. we can have Graph be a monad made up of `Node[]` with `runGraph` defined by somehow composing Rules

```

data PortType = ... deriving (Show, Read)

data Port = Port { portType :: PortType, portName :: String } deriving (Show, Read)

data Node = Node { inputPorts :: [Port], outputPorts :: [Port], principal :: Port } deriving (Show, Read)

```

Will need some creativity for the Rules to be defined more naturally, or it would end up just a function:

```

zeroAddRule :: Port -> [Port] -> Maybe [Port]

zeroAddRule target [addend]

    | target == outputPorts zero !! 0 = Just [addend]

    | otherwise = Nothing

```