functional-programming

问题 Background I am trying to compose 2 functions using Ramda, but I am having issue with pipe , meaning I don't know how to use it. Code Let's imagine I have a function that returns an array: var createQuery = params => [ getSQLQuery( params ), [ getMarket() ] ]; var getSQLQuery = ( { lang } ) => `My query is ${lang}`; var getMarket = () => "en_en" So, when calling createQuery({ lang: "es" }) I would have the following output: [ "My query is es", ["en_en"] ] ; Now, let's also assume I am a nasty

问题 I got a lot of help from this SO question around grabbing directories and searching files. I'm trying to conform my readPackageFiles function to use the Parallel function given to me; however, I'm struggling to it it work. Error: UnhandledPromiseRejectionWarning: TypeError: Cannot use 'in' operator to search for 'throws' in 1 at readFile (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/jsonfile/index.js:22:16) at Promise (/Users/harwood/udev/dotcom

问题 I am trying to multiply in Scheme using recursion, and I am able to do so with positive numbers but not negatives (they get stuck in an infinite loop). I assume the problem comes in the 3rd and 4th lines, which I wrote in an attempt to be able to handle negatives. Any help would be appreciated :) (define Multiply(lambda (x y) (if (eq? x 0) 0 (if (eq? y 0) 0 ;if either x or y are zero, return 0 (if (> 0 x) (- 0 (+ x (Multiply x (- y 1)))) (if (> 0 y) (- 0 (+ x (Multiply x (- y 1)))) (+ x

问题 I have two functions and they are executed depending of if statement. E.g.: if(value) { doA() } else { doB() } How to write function or object that will take the result and decide whether or not execute each function. I want to receive something like this: exists(result).doA() nothing(result).doB() I want to learn some functional programming in JavaScrit so I woud appreciate any source from which I can learn FP in JavaScript. 回答1: You could write something like this, for example: function

问题 Is there an equivalent construct in Javascript. If not, how would you create one? Here's a straightforward explanation of what the infix operator does in Haskell: What does the : infix operator do in Haskell? 回答1: JavaScript doesn't have a list type, but it has Array s. You can use... var newArr = [val].concat(arr); Alternatively, you could use unshift() to prepend to an array, but it mutates the original. JavaScript doesn't have a : operator, operator overloading or methods that look like

问题 I'm building a data pipelining tool and want to be able to compile a series of functions together. All the functions act on an iterable, and pass an iterable as a yielded value. So if f(x) filters, and g(x) edits, and h(x) generates a random value, then I want to be able to compose combinations of these so I can call f(g(h(x))) or h(f(g(x))) as per requirements. I'd like to be able to prepare these compositions (they have different parameter signatures beyond the initial iterable) before

问题 Consider the following numbers nested by vectors in a tree-structure (def tree [7 9 [7 5 3 [4 6 9] 9 3] 1 [2 7 9 9]]) My goal is to find the path to the first even number that can be found by traversing the tree: In the upper example this would be 4, the path from the root to this node would be [2 3 0] (def result [2 3 0]) I got some difficulties writing a function tho archive this. However, the following function finds the first even number, not its path: (defn find-even [x] (if (vector? x)

问题 I'm trying to learn JavaScript well and am practicing rebuilding some underscore functions. I'm trying to rebuild zip using map where there is an arbitrary number of arguments. Here is the solution I came up with, with pluck. I know that the underscore implementation itself uses _pluck, which internally uses Map, so I wanted to see if it was possible to do this with map... _.zip = function() { var argumentsArray = Array.prototype.slice.call(arguments); var longestArray = argumentsArray.sort

问题 Newbie to scala. I am trying to make this code to work for a few hours now . It is intended to update the List[Int](list of integers) with absolute values of the integers. Took a long time to figure out that List is immutable, so found that ListBuffer can be the saviour, but eventually in returning it back into the List form is seeing some issue i guess. def f (arr:List[Int]) : List[Int] = { val list = new scala.collection.mutable.ListBuffer[Int](); val len = arr.length; for ( i <- 0 to len)

问题 Maybe this is a stupid ask but I recently found myself using this abstraction often: async function giveMeAName(cbAsync, initValue) { return await Promise.all( initValue.map(cbAsync), ); } Question: Is this a common task to anyone else? If so, does it have a name? If not, maybe it's only partly realize, so does it remind you of anything? Otherwise, I can just delete the question. Currently I'm using this function for this set of instructions. Code below will get all directories of a path and