Non-allocating lambdas

[marcinjahn]

Looking through the code, I see that various methods accept lambdas, and there is no mechanism to avoid closure allocations.

Example:

Repository myService = ResolveMyService();
Maybe<Something> maybe = GetSomeMaybe();

maybe.Match(
  some: something => myService.DoSomething(something), // allocation
  none: () => myService.DoSomethingElse() // allocation
);

I think it'd be nice if there was an overload like:

public static void Match<T, TBag>(this Maybe<T> maybe, Func<T, TBag> some, Func<TBag> none, TBag bag)
{
  if (maybe.HasValue)
  {
    some(maybe.Value, bag);
  } 
  else
  {
    none(bag);
  }
}

Then, my example could be turned into:

Repository myService = ResolveMyService();
Maybe<Something> maybe = GetSomeMaybe();

maybe.Match(
  some: (something, service) => service.DoSomething(something), // no allocation
  none: (service) => service.DoSomethingElse(), // no allocation
  bag: myService // could also be some tuple with many items
);

What do you think about it? The naming I used (bag) might not be the best, maybe there's some better name for it.

[vkhorikov]

Yep, good idea. We probably have methods other than Match that could benefit from the same overloads.

[marcinjahn]

Yeah, definitely, it was just an example.