Tickers in Modelica

In Modelica, we don’t have a direct equivalent to Go’s tickers. However, we can simulate similar behavior using the built-in sample operator and discrete-time equations. Here’s how we can implement a similar concept:

model Tickers
  Real nextTick(start=0.5);
  discrete Real tickTime;
  Boolean stop(start=false);
  
equation
  when sample(0, 0.5) and not stop then
    tickTime = time;
    nextTick = time + 0.5;
    Modelica.Utilities.Streams.print("Tick at " + String(tickTime));
  end when;
  
  when time >= 1.6 then
    stop = true;
    Modelica.Utilities.Streams.print("Ticker stopped");
  end when;
end Tickers;

In this Modelica implementation:

1. We use a discrete variable nextTick to keep track of when the next tick should occur.
2. The sample(0, 0.5) operator generates events every 0.5 seconds, similar to the 500ms interval in the original example.
3. We use a when equation to print the tick time whenever a sample event occurs and the stop flag is false.
4. Another when equation sets the stop flag to true after 1.6 seconds, simulating the time.Sleep(1600 * time.Millisecond) in the original code.

To run this model:

$ modelica Tickers.mo
$ ./Tickers
Tick at 0.5
Tick at 1.0
Tick at 1.5
Ticker stopped

When we run this model, it should produce three ticks before stopping, similar to the original Go program.

Note that Modelica is primarily used for continuous-time physical system modeling, so this example is an adaptation of the concept rather than a direct translation. In real-world Modelica applications, you would typically use continuous-time equations and events for modeling physical systems rather than implementing timer-like behavior.