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Functions in Racket can be created with the lambda form. The form takes a list of arguments and a body. (lambda (x y) (* x y)) In the example above, the function takes in two arguments and returns the result of multiplying them. > ((lambda (x y) (* x y)) 4 4) 16 > ((lambda (x y) (* x y)...

Download and install Visual Studio Community 2015 Open Visual Studio Community Click File -> New -> Project Click Templates -> Visual C++ -> Win32 Console Application and then name the project MyFirstProgram. Click Ok Click Next in the following window. Check the Empty proj...

In many instances, you will want to send data from the R server to the JS client. Here is a very simple example: library(shiny) runApp( list( ui = fluidPage( tags$script( "Shiny.addCustomMessageHandler('message', function(params) { alert(params); });" ), ...

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. W3C DOM4 A simple method to add a class to an element is to append it to the end of the className property. This will no...

Thread.sleep causes the current thread to suspend execution for a specified period. This is an efficient means of making processor time available to the other threads of an application or other applications that might be running on a computer system. There are two overloaded sleep methods in the Thr...

To set a value in NSUserDefaults, you can use the following functions: Swift < 3 setBool(_:forKey:) setFloat(_:forKey:) setInteger(_:forKey:) setObject(_:forKey:) setDouble(_:forKey:) setURL(_:forKey:) Swift 3 In Swift 3 the names of function is changed to set insted of set folloed by ...

To get a value in NSUserDefaults you can use the following functions: Swift arrayForKey(_:) boolForKey(_:) dataForKey(_:) dictionaryForKey(_:) floatForKey(_:) integerForKey(_:) objectForKey(_:) stringArrayForKey(_:) stringForKey(_:) doubleForKey(_:) URLForKey(_:) Objective-C -(nullab...

One of the most useful queries for end users of large RDBMS's is a search of an information schema. Such a query allows users to rapidly find database tables containing columns of interest, such as when attempting to relate data from 2 tables indirectly through a third table, without existing knowl...

REM This is a comment REM is the official comment command.

::This is a label that acts as a comment The double-colon :: comment shown above is not documented as being a comment command, but it is a special case of a label that acts as a comment. Caution: when labels are used as comments within a bracketed code block or for command, the command processor...

It is also possible to use variables as comments. This can be useful to conditionally prevent commands being executed: @echo off setlocal if /i "%~1"=="update" (set _skip=) Else (set _skip=REM) %_skip% copy update.dat %_skip% echo Update applied ... When using the ab...

Environment variables can be defined before the meteor call, like so: PORT=4000 meteor NODE_ENV="staging" meteor

Method 1 Gson gson = new Gson(); String json = "[ \"Adam\", \"John\", \"Mary\" ]"; Type type = new TypeToken<List<String>>(){}.getType(); List<String> members = gson.fromJson(json, type); Log.v("Members", members.toString());...

Angular has some magic under its hood. it enables binding DOM to real js variables. Angular uses a loop, named the "digest loop", which is called after any change of a variable - calling callbacks which update the DOM. For example, the ng-model directive attaches a keyup eventListener to...

angular.module('app', []) .controller('myController', ['$scope', function($scope){ $scope.person = { name: 'John Doe' }; }]); <div ng-app="app" ng-conroller="myController"> <input ng-model="person.name" /> <div ng-repeat="number i...

In javascript, assigning a non-primitive value (Such as Object, Array, Function, and many more), keeps a reference (an address in the memory) to the assigned value. Assigning a primitive value (String, Number, Boolean, or Symbol) to two different variables, and changing one, won't change both: var...

Be careful, this approach might be considered as a bad design for angular apps, since it requires programmers to remember both where functions are placed in the scope tree, and to be aware of scope inheritance. In many cases it would be preferred to inject a service (Angular practice - using scope ...

To copy files from the build context in a Docker image, use the COPY instruction: COPY localfile.txt containerfile.txt If the filename contains spaces, use the alternate syntax: COPY ["local file", "container file"] The COPY command supports wildcards. It can be used for ...

To declare exposed ports from a Dockerfile use the EXPOSE instruction: EXPOSE 8080 8082 Exposed ports setting can be overridden from the Docker commandline but it is a good practice to explicitly set them in the Dockerfile as it helps understand what an application does.