anonymous-function

问题 I am trying to wrap my head around the syntax of Haskell. This problem is very simple to solve logically. I have to break up a list of positive and negative integers and group them such that [1,2,3,-1,-2,-3,1,2,3] becomes [[1,2,3],[-1,-2,-3], [1,2,3]] I would like to use a higher order function, foldr to be able to do that with an anonymous function taking in two arguements. This is what I have so far. split = foldr (\ x y -> if (x > 0) then if (head (head y)) < 0 then [x] : y else x : head y

问题 If I have the code below, where I pass two functions as a parameters into the function sayHi , is this an example of a callback? I notice there are two ways of running these 'parameter functions': either as below, we I call the functions where they are defined (as arguments), or alternatively where I call the parameter in the sayHi function. Would this be the difference between a callback and an anonymous function? function sayHi(name, testForTrue) { if (testForTrue == true) { console.log

问题 Can someone help me resolve this problem I tried everything. I usually know how to resolve that problem but not with anonymous method. DelegateCommand has 2 constructors. 1) public DelegateCommand (Action executeMethod) 2) public DelegateCommand (Action executeMethod, Func canExecute). I wanna know is it possible some how to remove that warning. Async and await are needed otherwise my method: enterButtonClicked(); would be called synchronously. ... public DelegateCommand EnterButton { get;

问题 Is there a way to do this in php? //in a class public static function myFunc($x = function($arg) { return 42+$arg; }) { return $x(8); //return 50 if default func is passed in } 回答1: PHP Default function arguments can only be of scalar or array types: The default value must be a constant expression, not (for example) a variable, a class member or a function call. From: PHP Manual / Function Arguments / Default argument values How about: public static function myFunc($x = null) { if (null ===

问题 I was reading a post about how to fire a function after a window resize was complete and came across some examples that assigned self executing anonymous functions to variables: var delay = (function(){ var timer = 0; return function(callback, ms){ clearTimeout (timer); timer = setTimeout(callback, ms); }; })(); $(window).resize(function() { delay(function(){ alert('Resize...'); //... }, 500); }); What is the difference/benefit of making the function operand self executing as opposed to it's

问题 Because of the complexity of this application, I have a need to wrap Facebook API calls, like so. //In main file, read is always undefined var read = fb_connect.readStream(); // In fb_wrapper.js function readStream () { var stream; FB.api('/me/feed', {limit:10000}, function (response) { stream = response.data; }); return stream; } I know that due to the asynchronous nature of the call, the rest of the readStream() function will return stream (which has no value). I am having trouble finding a

问题 I've created a function that gets console input from the user as-long as it fits a filter so to speak. public delegate TResult OutFunc<in T, TValue, out TResult>(T arg1, out TValue arg2); public static T PromptForInput<T>(string prompt, OutFunc<string, T, bool> filter) { T value; do { Console.Write(prompt); } while (!filter(Console.ReadLine(), out value)); return value; } This works great when I call the method as I do below. which gets a number from the user as long as it parses to an int

问题 I need to build up a vector of non-linear equations to be used in fsolve to solve it. But I should make each element of the vector in each loop iteration. How can I make up such a vector? In fact, I can not use cell array. How can I convert a cell array like {@(x) x(1)+x(2)^2; @(x) x(1)-2*(x(2))} into an array like @(x) [ x(1)+x(2)^2 ; x(1)-2*(x(2))] ? Because I want to use fsolve to solve the system of non-linear equations. 回答1: Use func2str to get the function definitions in string and use

问题 Is it possible to get the number of arguments expected of an anonymous function in PHP? I'm aware of ReflectionMethod, but that seems to only work if the method is defined on a class. In my case, the anonymous function is either going to have 1 or two arguments. I'd prefer to do the checking correctly, rather than wrapping the first call in a try/catch, and trying again with 2 parameters if the first has failed. 回答1: Try this: // returns the arity of the given closure function arity($lambda)

问题 I have an integrated error expression E = int[ abs(x- p )^2 ]dx with limits x|0 to x| L . The variable p is a polynomial of the form 2*(a*sin(x)+b(a)*sin(2*x)+c(a)*sin(3*x)) . In other words, both coefficients b and c are known expressions of a . An additional equation is given as dE/da = 0 . If the upper limit L is defined, the system of equations is closed and I can solve for a , giving the three coefficients. I managed to get an optimization routine to solve for a purely based on