public override RecursionResult <KObject> Combine(KObject args, KEnvironment env, Continuation <KObject> cont)
{
int len = KPair.Length(args);
if (len < 2 || len > 3)
{
return(CPS.Error("extend-continuation: argument mismatch", cont));
}
KContinuation argC = First(args) as KContinuation;
KApplicative argA = Second(args) as KApplicative;
KEnvironment argE = len == 3 ? Third(args) as KEnvironment : new KEnvironment();
if (argC == null || argA == null || argE == null)
{
return(CPS.Error("extend-continuation: mismatching arguments", cont));
}
var nc = new Continuation <KObject>((val, ctxt) =>
{
return(CPS.Next(() => Evaluator.rceval(new KPair(argA.Combiner, val, true), argE, argC.Value), argC.Value));
}, argC.Value, argA);
return(Return(new KContinuation(nc), cont));
}