internal MFist(Fist src, Funf fun)
{
switch (src)
{
case (var head, Nilf _):
this.Head = new Lazy <dynamic>(() =>
{
var h = call(fun, head);
return(h);
});
this.Tail = new Lazy <Fist>(() => nilf);
break;
case var _:
this.Head = new Lazy <dynamic>(() =>
{
var h = call(fun, src.head);
return(h);
});
this.Tail = new Lazy <Fist>(() => new MFist(src.tail, fun));
break;
}
}
public static Fist create(Fist source, Funf predicate) => drop_until(source, predicate) switch
{