Are you talking about this function? reduce <U> U reduce(U identity, BiFunction<U,? super T,U> accumulator, BinaryOperator<U> combiner) Performs a reduction on the elements of this stream, using the provided identity, accumulation and combining functions. This is equivalent to: U result = identity; for (T element : this stream) result = accumulator.apply(result, element) return result; but … Read more
The reason is expressed in this post from Brian Goetz himself: We are “reclaiming” the syntactic real estate of “_” from the space of identifiers for use in future language features. However, because there are existing programs that might use it, it is a warning for identifiers that occur in existing syntactic positions for 8, … Read more
The good news is: You don’t need to use map or filter at all, you can use generator expressions (lazy) or list comprehensions (eager) instead and thus avoid lambdas completely. So instead of: lines = map(lambda x: x.strip(), sys.stdin) Just use: # You can use either of those in Python 2 and 3, but map … Read more
You would have to do .filter(((Predicate<String>) String::isEmpty).negate()) If you want, you can define static<T> Predicate<T> not(Predicate<T> p) { return t -> !p.test(t); } and then .filter(not(String::isEmpty)) but I would just stick with v -> !v.isEmpty()
I wouldn’t waste my time thinking whether the lambda expressions are a violation of OO principles. Its goal is to increase the power of a language and not to write an OO code, I don’t see how lambdas can violate encapsulation, inheritance or polymorphism. This article explains how Java handles lambda expressions: What’s interesting about … Read more
You could, of course, “make the outer value mutable” via a trick: public void test() { String[] x = new String[1]; List<String> list = Arrays.asList(“a”, “b”, “c”, “d”); list.forEach(n -> { if (n.equals(“d”)) x[0] = “match the value”; }); } Get ready for a beating by the functional purist on the team, though. Much nicer, … Read more
To workaround the CORS issue with Apollo you have to pass the no-cors option to the underlying fetch. import ApolloClient from “apollo-boost”; const client = new ApolloClient({ uri: “your client uri goes here”, fetchOptions: { mode: ‘no-cors’, }, }); This is not a specific Apollo problem, rather a configuration that is meant to be tackled … Read more
Code for joining 3 tables is: var list = dc.Orders. Join(dc.Order_Details, o => o.OrderID, od => od.OrderID, (o, od) => new { OrderID = o.OrderID, OrderDate = o.OrderDate, ShipName = o.ShipName, Quantity = od.Quantity, UnitPrice = od.UnitPrice, ProductID = od.ProductID }).Join(dc.Products, a => a.ProductID, p => p.ProductID, (a, p) => new { OrderID = a.OrderID, … Read more
Lambdas in C# do not have types, until they are used in a context that casts them to a delegate or Expression type. That’s why you cannot do the following: var x = () => “some lambda”; You might enjoy Eric Lippert’s Series on Lambda Expressions vs Anonymous Methods Lambda vs Anon – Part One … Read more