private static async Task <Maybe <TResult> > Run <TResult>(EffStateMachine <TResult> stateMachine)
{
while (true)
{
stateMachine.MoveNext();
switch (stateMachine.Position)
{
case StateMachinePosition.Result:
return(Maybe <TResult> .Just(stateMachine.Result));
case StateMachinePosition.Exception:
throw stateMachine.Exception !;
case StateMachinePosition.TaskAwaiter:
await stateMachine.TaskAwaiter !.Value;
break;
case StateMachinePosition.EffAwaiter:
var awaiter = stateMachine.EffAwaiter !;
var handler = new MaybeEffectHandlerImpl <TResult>(stateMachine);
await awaiter.Accept(handler);
return(handler.Result);
default:
throw new Exception($"Invalid state machine position {stateMachine.Position}.");
}
}
}
public static Maybe <TResult> Run <TResult>(Eff <TResult> eff)
{
switch (eff)
{
case ExceptionEff <TResult> setException:
throw setException.Exception;
case ResultEff <TResult> setResult:
return(Maybe <TResult> .Just(setResult.Result));
case DelayEff <TResult> delay:
return(Run(delay.Continuation.MoveNext()));
case AwaitEff <TResult> awaitEff:
var handler = new MaybeEffectHandlerImpl <TResult>(awaitEff.Continuation);
awaitEff.Awaiter.Accept(handler);
return(handler.Result);
default:
throw new NotSupportedException($"{eff.GetType().Name}");
}
}
