With () => {} and function () {} we are getting two very similar ways to write functions in ES6. In other languages lambda functions often distinguish themselves by being anonymous, but in ECMAScript any function can be anonymous. Each of the two types have unique usage domains (namely when this needs to either be … Read more
I’m using C# on Framework 3.5. I’m looking to quickly sort a Generic List<T>. For the sake of this example, let’s say I have a List of a Person type with a property of lastname. How would I sort this List using a lambda expression? List<Person> people = PopulateList(); people.OrderBy(???? => ?????) 9 s 9 … Read more
I was playing around with Java 8 lambdas to easily filter collections. But I did not find a concise way to retrieve the result as a new list within the same statement. Here is my most concise approach so far: List<Long> sourceLongList = Arrays.asList(1L, 10L, 50L, 80L, 100L, 120L, 133L, 333L); List<Long> targetLongList = new … Read more
I’m having trouble with a query written in LINQ and Lambda. So far, I’m getting a lot of errors here’s my code: int id = 1; var query = database.Posts.Join(database.Post_Metas, post => database.Posts.Where(x => x.ID == id), meta => database.Post_Metas.Where(x => x.Post_ID == id), (post, meta) => new { Post = post, Meta = meta … Read more
I know how to create a reference to a method that has a String parameter and returns an int, it’s: Function<String, Integer> However, this doesn’t work if the function throws an exception, say it’s defined as: Integer myMethod(String s) throws IOException How would I define this reference? 26 s 26 You’ll need to do one … Read more
Is there a better way to get the Property name when passed in via a lambda expression? Here is what i currently have. eg. GetSortingInfo<User>(u => u.UserId); It worked by casting it as a memberexpression only when the property was a string. because not all properties are strings i had to use object but then … Read more
I have to find the average of a list in Python. This is my code so far from functools import reduce l = [15, 18, 2, 36, 12, 78, 5, 6, 9] print(reduce(lambda x, y: x + y, l)) I’ve got it so it adds together the values in the list, but I don’t know … Read more
Using reflection, how can I get all types that implement an interface with C# 3.0/.NET 3.5 with the least code, and minimizing iterations? This is what I want to re-write: foreach (Type t in this.GetType().Assembly.GetTypes()) if (t is IMyInterface) ; //do stuff 19 s 19 Mine would be this in c# 3.0 🙂 var type … Read more
For a person without a comp-sci background, what is a lambda in the world of Computer Science? 23 s 23 Lambda comes from the Lambda Calculus and refers to anonymous functions in programming. Why is this cool? It allows you to write quick throw away functions without naming them. It also provides a nice way … Read more
Right, so I have an enumerable and wish to get distinct values from it. Using System.Linq, there’s, of course, an extension method called Distinct. In the simple case, it can be used with no parameters, like: var distinctValues = myStringList.Distinct(); Well and good, but if I have an enumerable of objects for which I need … Read more
