Question

What design patterns have you found work well with lambda expressions/functions?

Answer 1

Lambdas are actively used in IoC containers and DI (for example mock frameworks) nowadays

I can see following GoF patterns in this area:

Moq is using Proxy pattern with active use of lambdas; for example:

var mock = new Mock<IFoo>();
mock.Setup(foo => foo.DoSomething("ping")).Returns(true);

You can find that lambdas help to implement Singleton pattern in IoC containers, for example autofac, without limiting yourself in testability, like usual Singleton does:

builder.Register(c => new MyClass()).SingleInstance();

And Factory Method pattern by means of proving a constructor call with parameters as type registration:

builder
    .Register(c => new ObjectContainer(ConnectionStrings.CustomerDB))
    .As<IObjectContainer>()
    .Named("CustomerObjectContainer");

Also

Expression <TDelegate> class is also closely related to Interpreter pattern