// M<T> -> Func<T, TResult> -> M<TResult>
public static State <TState, TResult> Select <TState, T, TResult>(
this State <TState, T> self, Func <T, TResult> operation)
{
Debug.Assert(self != null);
Debug.Assert(operation != null);
return(state =>
{
var stateResult = self(state);
return StateResult.Create(
stateResult.State,
operation(stateResult.Value));
});
}
public static State <TState, Unit> Modify <TState>(Func <TState, TState> operation)
{
Debug.Assert(operation != null);
return(state => StateResult.Create(operation(state), Unit.Value));
}
public static State <TState, TState> Get <TState>()
{
return(state => StateResult.Create(state, state));
}
public static State <TState, Unit> Put <TState>(TState state)
{
return(_ => StateResult.Create(state, Unit.Value));
}
public static State <TState, T> ToState <TState, T>(this T value)
{
return(state => StateResult.Create(state, value));
}