Laymens terms: A recursive function is a function that calls itself A bit more in depth: If the function keeps calling itself, how does it know when to stop? You set up a condition, known as a base case. Base cases tell our recursive call when to stop, otherwise it will loop infinitely. What was … Read more
For example when you have function that calls it recursively, and you want to get synchronized access to it: void foo() { … mutex_acquire(); … foo(); … mutex_release(); } without a recursive mutex you would have to create an “entry point” function first, and this becomes cumbersome when you have a set of functions that … Read more
Here’s an alternative to the opt-in attribute approach. I believe this will traverse the object-graph properly and validate everything. public bool TryValidateObjectRecursive<T>(T obj, List<ValidationResult> results) { bool result = TryValidateObject(obj, results); var properties = obj.GetType().GetProperties().Where(prop => prop.CanRead && !prop.GetCustomAttributes(typeof(SkipRecursiveValidation), false).Any() && prop.GetIndexParameters().Length == 0).ToList(); foreach (var property in properties) { if (property.PropertyType == typeof(string) || … Read more
This is of course a “feature”. The ConcurrentHashMap.computeIfAbsent() Javadoc reads: If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless null. The entire method invocation is performed atomically, so the function is applied at most once per … Read more
Try this: Dir.glob(“#{folder}/**/*.pdf”) which is the same as Dir[“#{folder}/**/*.pdf”] Where the folder variable is the path to the root folder you want to search through.
The problem lies in your base case. “The height of a tree is the length of the path from the root to the deepest node in the tree. A (rooted) tree with only a node (the root) has a height of zero.” – Wikipedia If there is no node, you want to return -1 not … Read more
The issue is that Python has an internal limit on number of recursive function calls. That limit is configurable as shown in Quentin Coumes’ answer. However, too deep a function chain will result in a stack overflow. This underlying limitation¹ applies to both C++ and Python. This limitation also applies to all function calls, not … Read more
Church Turing thesis highlights the equivalence between different computability models. Using recursion we don’t need a mutable state while solving some problem, and this make possible to specify a semantic in simpler terms. Thus solutions can be simpler, in a formal sense. I think that Prolog shows better than functional languages the effectiveness of recursion … Read more
Some explanations are in order! What is the id function for? What is the role of? Why should we need it here? id is the identity function, id x = x, and is used as the equivalent of zero when building up a chain of functions with function composition, (.). You can find it defined … Read more
You’re defining a function in terms of itself. In general, fibonnaci(n) = fibonnaci(n – 2) + fibonnaci(n – 1). We’re just representing this relationship in code. So, for fibonnaci(7) we can observe: fibonacci(7) is equal to fibonacci(6) + fibonacci(5) fibonacci(6) is equal to fibonacci(5) + fibonacci(4) fibonacci(5) is equal to fibonacci(4) + fibonacci(3) fibonacci(4) is … Read more