Another important but subtle difference between procs created with lambda and procs created with Proc.new is how they handle the return statement: In a lambda-created proc, the return statement returns only from the proc itself In a Proc.new-created proc, the return statement is a little more surprising: it returns control not just from the proc, … Read more
The simple answer to your question is: You can’t, at least not directly. And it’s not your fault. Oracle messed it up. They cling on the concept of checked exceptions, but inconsistently forgot to take care of checked exceptions when designing the functional interfaces, streams, lambda etc. That’s all grist to the mill of experts … Read more
… starting in Java SE 8, a local class can access local variables and parameters of the enclosing block that are final or effectively final. A variable or parameter whose value is never changed after it is initialized is effectively final. For example, suppose that the variable numberLength is not declared final, and you add … Read more
If you need this, you shouldn’t use forEach, but one of the other methods available on streams; which one, depends on what your goal is. For example, if the goal of this loop is to find the first element which matches some predicate: Optional<SomeObject> result = someObjects.stream().filter(obj -> some_condition_met).findFirst(); (Note: This will not iterate the … Read more
I find that odd not so much because of the name, but because the lambda is unnecessary; it could use an anonymous-type and be more flexible: .Attributes(new { style = “width:100%”, @class=”foo”, blip=123 }); This is a pattern used in much of ASP.NET MVC (for example), and has other uses (a caveat, note also Ayende’s … Read more
Guido van Rossum (the inventor of Python) answers this exact question himself in an old blog post. Basically, he admits that it’s theoretically possible, but that any proposed solution would be un-Pythonic: “But the complexity of any proposed solution for this puzzle is immense, to me: it requires the parser (or more precisely, the lexer) … Read more
Lambdas are purely a call-site construct: the recipient of the lambda does not need to know that a Lambda is involved, instead it accepts an Interface with the appropriate method. In other words, you define or use a functional interface (i.e. an interface with a single method) that accepts and returns exactly what you want. … Read more
The syntax you’re looking for: lambda x: True if x % 2 == 0 else False But you can’t use print or raise in a lambda.
If you mean an in-place sort (i.e. the list is updated): people.Sort((x, y) => string.Compare(x.LastName, y.LastName)); If you mean a new list: var newList = people.OrderBy(x=>x.LastName).ToList(); // ToList optional
A while ago our team migrated all its code (a mid-sized AngularJS app) to JavaScript compiled using Traceur Babel. I’m now using the following rule of thumb for functions in ES6 and beyond: Use function in the global scope and for Object.prototype properties. Use class for object constructors. Use => everywhere else. Why use arrow … Read more