Enums in CLIPS

Based on the input, the target language is Python. Here’s the equivalent code and explanation translated from the provided example:

Our enum type ServerState has an underlying int type.

The possible values for ServerState are defined as constants.

By implementing the __str__ method, values of ServerState can be printed out or converted to strings.

If we have a value of type int, we cannot pass it to transition - the compiler will complain about type mismatch. This provides some degree of compile-time type safety for enums.

from enum import Enum, auto

class ServerState(Enum):
    StateIdle = auto()
    StateConnected = auto()
    StateError = auto()
    StateRetrying = auto()

state_name = {
    ServerState.StateIdle: "idle",
    ServerState.StateConnected: "connected",
    ServerState.StateError: "error",
    ServerState.StateRetrying: "retrying",
}

def __str__(self):
    return state_name[self]

def transition(s):
    if s == ServerState.StateIdle:
        return ServerState.StateConnected
    elif s == ServerState.StateConnected or s == ServerState.StateRetrying:
        return ServerState.StateIdle
    elif s == ServerState.StateError:
        return ServerState.StateError
    else:
        raise ValueError(f"unknown state: {s}")

def main():
    ns = transition(ServerState.StateIdle)
    print(ns)
    ns2 = transition(ns)
    print(ns2)

if __name__ == "__main__":
    main()

To run the program, execute the Python script.

$ python3 enums.py
connected
idle

By translating the provided example to Python, we have used the Enum class to define enumerated constants and provided a transition function to simulate state transitions. The __str__ method is used to convert enum values to their string representations. This ensures a similar approach to handling enums in Python as described in the original example.