Tutorial by Examples: ce

() is a Monoid. Since there is only one value of type (), there's only one thing mempty and mappend could do: instance Monoid () where mempty = () () `mappend` () = ()

SharedPreferences allows you to store primitive data types only (boolean, float, long, int, String, and string set). You cannot store more complex objects in SharedPreferences, and as such is really meant to be a place to store user settings or similar, it's not meant to be a database to keep user d...

Because of the reasons explained in Remarks section you can't simply do this (unless you want to count occurrences of a specific code-unit): int count = text.Count(x => x == ch); You need a more complex function: public static int CountOccurrencesOf(this string text, string character) { ...

Sometimes a element needs to be created outside of the usual object structure in the fxml. This is where Define Blocks come into play: Contents inside a <fx:define> element are not added to the object created for the parent element. Every child element of the <fx:define> needs a fx:id...

Press Ctrl + v to enter into visual block mode. Use ↑ / ↓ / j / k to select multiple lines. Press Shift + i and start typing what you want. After you press Esc, the text will be inserted into all the lines you selected. Remember that Ctrl+c is not 100% equivalent to Esc and will not work in this...

You can bind to a property of an ancestor in the visual tree by using a RelativeSource binding. The nearest control higher in the visual tree which has the same type or is derived from the type you specify will be used as the binding's source: <Grid Background="Blue"> <Grid ...

PS > Get-Member -InputObject $anObjectInstance This will return all members of the type instance. Here is a part of a sample output for String instance TypeName: System.String Name MemberType Definition ---- ---------- ---------- Clone ...

composer update composer update will update our dependencies as they are specified in composer.json. For example, if our project uses this configuration: "require": { "laravelcollective/html": "2.0.*" } Supposing we have actually installed the 2.0.1 version ...

For performance reasons you should minimize the number of fields you are requesting from the API. You can use the select property to do so. This example fetches the name property of all accounts: $.ajax({ url: Xrm.Page.context.getClientUrl() + '/api/data/v8.0/accounts?$select=name', head...

Controls that can be bound with data can make use of SqlDataSource controls. The SqlDataSource control not only allows you to retrieve data from a database, but also edit and sort the data. Retrieving Data Stored Procedure: <asp:SqlDataSource ID="SqlDataSourceEmployees" runat=&q...

When is an IEnumerable<T> a subtype of a different IEnumerable<T1>? When T is a subtype of T1. IEnumerable is covariant in its T parameter, which means that IEnumerable's subtype relationship goes in the same direction as T's. class Animal { /* ... */ } class Dog : Animal { /* ... */ }...

When is an IComparer<T> a subtype of a different IComparer<T1>? When T1 is a subtype of T. IComparer is contravariant in its T parameter, which means that IComparer's subtype relationship goes in the opposite direction as T's. class Animal { /* ... */ } class Dog : Animal { /* ... */ }...

This example show how you can check if a service already exists (i.e., is installed on the machine) or not. This code requires only the lowest privileges necessary, so each process can perform the check, no matter what level of security it is running at. #define UNICODE #define _UNICODE #include ...

IList<T> is never a subtype of a different IList<T1>. IList is invariant in its type parameter. class Animal { /* ... */ } class Dog : Animal { /* ... */ } IList<Dog> dogs = new List<Dog>(); IList<Animal> animals = dogs; // type error There is no subtype relat...

Interfaces may have variant type parameters. interface IEnumerable<out T> { // ... } interface IComparer<in T> { // ... } but classes and structures may not class BadClass<in T1, out T2> // not allowed { } struct BadStruct<in T1, out T2> // not allo...

This will give current system version. Objective-C NSString *version = [[UIDevice currentDevice] systemVersion] Swift let version = UIDevice.currentDevice().systemVersion Swift 3 let version = UIDevice.current.systemVersion

Destructuring also gives you the ability to interpret a sequence as a map: (def my-vec [:a 1 :b 2]) (def my-lst '("smthg else" :c 3 :d 4)) (let [[& {:keys [a b]}] my-vec [s & {:keys [c d]} my-lst] (+ a b c d)) ;= 10 It is useful for defining functions with named p...

In oracle, the difference (in days and/or fractions thereof) between two DATEs can be found using subtraction: SELECT DATE '2016-03-23' - DATE '2015-12-25' AS difference FROM DUAL; Outputs the number of days between the two dates: DIFFERENCE ---------- 89 And: SELECT TO_DATE( '201...

Following code will release the lock. There will be no problem. Behind the scenes lock statement works as try finally lock(locker) { throw new Exception(); } More can be seen in the C# 5.0 Specification: A lock statement of the form lock (x) ... where x is an expression of a referenc...

We create a new concurrent process by calling the spawn function. The spawn function will get as parameter a function Fun that the process will evaluate. The return value of the spawn function is the created process identifier (pid). 1> Fun = fun() -> 2+2 end. #Fun<erl_eval.20.52032458&gt...