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Since Proxy contains no runtime information, there is never a need to pattern-match on the Proxy constructor. So a common idiom is to abstract over the Proxy datatype using a type variable. showread :: forall proxy a. (Show a, Read a) => proxy a -> String -> String showread _ = (show :: a...

Since Proxy contains no runtime information, you can always write a natural transformation f a -> Proxy a for any f. proxy :: f a -> Proxy a proxy _ = Proxy This is just like how any given value can always be erased to (): unit :: a -> () unit _ = () Technically, Proxy is the term...

There are several different ways to specify props in JSX. JavaScript Expressions You can pass any JavaScript expression as a prop, by surrounding it with {}. For example, in this JSX: <MyComponent count={1 + 2 + 3 + 4} /> Inside the MyComponent, the value of props.count will be 10, becau...

Description: mov copies values of bits from source argument to destination argument. Common source/destination are registers, usually the fastest way to manipulate values with[in] CPU. Another important group of source_of/destination_for values is computer memory. Finally some immediate values m...

This is usually used for renaming or shortening long namespace references such referring to components of a library. namespace boost { namespace multiprecision { class Number ... } } namespace Name1 = boost::multiprecision; // Both Type declarations are equivale...

Alias Declaration are affected by preceding using statements namespace boost { namespace multiprecision { class Number ... } } using namespace boost; // Both Namespace are equivalent namespace Name1 = boost::multiprecision; namespace Name2 = multiprecision; ...

PyMongo is a native Python driver for MongoDB. Install PyMongo pip install pymongo Create a connection Use MongoClient to create a connection. MongoClient defaults to MongoDB instance running on localhost:27017 if not specified. from pymongo import MongoClient client = MongoClient() Acce...

Php arrayiterator allows you to modify and unset the values while iterating over arrays and objects. Example: $array = ['1' => 'apple', '2' => 'banana', '3' => 'cherry']; $arrayObject = new ArrayObject($array); $iterator = $arrayObject->getIterator(); for($iterator; $iterator-...

GridView definition on ASPX page As shown below, first column of grid is defined as a checkbox column, which is conditionally cleared as shown in further examples below (the header checkbox is only for selecting/un-selecting all rows on current page, but same can be extended for all on grid easily)...

MongoDB stores data records as BSON documents. BSON is the binary representation of JSON. $ python >>> from pymongo import MongoClient >>> client = MongoClient() >>> col = client.mydb.test Create Insert a single document insert_one(document) >>> result = ...

Although not necessary in PHP however it is a very good practice to initialize variables. Uninitialized variables have a default value of their type depending on the context in which they are used: Unset AND unreferenced var_dump($unset_var); // outputs NULL Boolean echo($unset_bool ? "tr...

Go to File > Settings > Keymap and select the Keymaps option from: Mac OS X Emacs Visual Studio Eclise Netbeans Jbuilder and others, to map the shortcuts to the wanted tool ones.

Available since Rails 4.2, Active Job is a framework for declaring jobs and making them run on a variety of queuing backends. Recurring or punctual tasks that are not blocking and can be run in parallel are good use cases for Active Jobs.

class UserUnsubscribeJob < ApplicationJob queue_as :default def perform(user) # this will happen later user.unsubscribe end end

instanceof requires that the variable is of type any. This code (try it): class Pet { } class Dog extends Pet { bark() { console.log("woof"); } } class Cat extends Pet { purr() { console.log("meow"); } } function example(foo: any) { ...

typeof is used when you need to distinguish between types number, string, boolean, and symbol. Other string constants will not error, but won't be used to narrow types either. Unlike instanceof, typeof will work with a variable of any type. In the example below, foo could be typed as number | str...

You can declare functions that serve as type guards using any logic you'd like. They take the form: function functionName(variableName: any): variableName is DesiredType { // body that returns boolean } If the function returns true, TypeScript will narrow the type to DesiredType in any bl...

This error message may be produced by the OpenSSH ssh client. It means that the TCP connection between the client and the server was abnormally closed by the server immediately after being accepted. Common reasons for this message include: The SSH server process is malfunctioning--for example, it...

This error message may be produced by the OpenSSH ssh client. It means that the TCP connection between the client and the server was closed by the server immediately after being accepted. This message generally indicates the SSH server has been configured not to accept connections from the client fo...

$ rails g job user_unsubscribe