functional-programming

问题 I have got two arrays of objects. I want to filter data based on permissionObj. This is coming from database. Here are arrays of sub-arrays in the permissionObj. let permissionObj = [ { "Deposit": [{ label: "can create", value: "can_create" }, ] }, { "Journals": [{ label: "can create", value: "can_create" }] }, { "Dashboard": [{ label: "can view", value: "can_view" }] }, ] this is static data. I want to compare this data based on permission. const PubSidebar = [{ label: "Dashboard", value:

问题 I have got two arrays of objects. I want to filter data based on permissionObj. This is coming from database. Here are arrays of sub-arrays in the permissionObj. let permissionObj = [ { "Deposit": [{ label: "can create", value: "can_create" }, ] }, { "Journals": [{ label: "can create", value: "can_create" }] }, { "Dashboard": [{ label: "can view", value: "can_view" }] }, ] this is static data. I want to compare this data based on permission. const PubSidebar = [{ label: "Dashboard", value:

问题 I have generated a Stream in Java 8 with Files.walk() method from java.nio library. The problem is that the method includes by default the root path but I do not want this element. I have solved in this case with this code using filter() method: public void listFiles(String directoryPath) { try { Path root = Paths.get(directoryPath); Files.walk(root,1) .filter(x -> !x.equals(root)) .forEach(System.out::println); } catch (IOException ex) { System.err.println("Error reading file: " +

问题 I have generated a Stream in Java 8 with Files.walk() method from java.nio library. The problem is that the method includes by default the root path but I do not want this element. I have solved in this case with this code using filter() method: public void listFiles(String directoryPath) { try { Path root = Paths.get(directoryPath); Files.walk(root,1) .filter(x -> !x.equals(root)) .forEach(System.out::println); } catch (IOException ex) { System.err.println("Error reading file: " +

问题 Is there any way to get the following working in Swift 3? let button = UIButton().apply { $0.setImage(UIImage(named: "UserLocation"), for: .normal) $0.addTarget(self, action: #selector(focusUserLocation), for: .touchUpInside) $0.translatesAutoresizingMaskIntoConstraints = false $0.backgroundColor = UIColor.black.withAlphaComponent(0.5) $0.layer.cornerRadius = 5 } The apply<T> function should take a closure of type (T)->Void , run it passing self into it, and then simply return self . Another

问题 I have two arrays of nested objects. I want to filter data based on permissionObj. This is coming from database. Here are arrays of sub-arrays in the permissionObj. I need to do another condition in reduce function . For example , if Pubsidebar value is token is public, I want to keep static content {label: "test",value: "public"} without filtering with permissionObj and if other key and value is match with permissionObj,then it will be push inside token . let permissionObj = [ { 'OA deal': [

问题 I was trying to construct functional program for parsing IP address. I am seeing an error. I wanted a simpler code which differentiates ipv4 to ipv6. Here is the JAVA code. import java.util.regex.Pattern; class Solution { String chunkIPv4 = "([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])"; Pattern pattenIPv4 = Pattern.compile("^(" + chunkIPv4 + "\\.){3}" + chunkIPv4 + "$"); String chunkIPv6 = "([0-9a-fA-F]{1,4})"; Pattern pattenIPv6 = Pattern.compile("^(" + chunkIPv6 + "\\:){7}" +

问题 Looks like I have a pretty clear understanding what a Monoid is in Haskell, but last time I heard about something called a free monoid. What is a free monoid and how does it relate to a monoid? Can you provide an example in Haskell? 回答1: In a programming context, I usually translate free monoid to [a] . In his excellent series of articles about category theory for programmers, Bartosz Milewski describes free monoids in Haskell as the list monoid (assuming one ignores some problems with

问题 I've been reading these links: https://reactjs.org/docs/hooks-faq.html#how-do-i-implement-shouldcomponentupdate https://reactjs.org/blog/2018/10/23/react-v-16-6.html In the first link it says (https://reactjs.org/docs/hooks-faq.html#from-classes-to-hooks): shouldComponentUpdate: See React.memo The second link also states that: Class components can bail out from rendering when their input props are the same using PureComponent or shouldComponentUpdate. Now you can do the same with function

问题 Is there a way in python to call filter on a list where the filtering function has a number of arguments bound during the call. For example is there a way to do something like this: >> def foo(a,b,c): return a < b and b < c >> myList = (1,2,3,4,5,6) >> filter(foo(a=1,c=4),myList) >> (2,3) This is to say is there a way to call foo such that a=1, c=4, and b gets bound to the values in myList? 回答1: You can create a closure for this purpose: def makefilter(a, c): def myfilter(x): return a < x < c