Tutorial by Examples: me

An interesting but rather unknown usage of Active Patterns in F# is that they can be used to validate and transform function arguments. Consider the classic way to do argument validation: // val f : string option -> string option -> string let f v u = let v = defaultArg v "Hello&quo...

Time and date come in a number of different types in Java: The now historic Date and Calendar, and the more recent LocalDate and LocalDateTime. And Timestamp, Instant, ZonedLocalDateTime and the Joda-time types. On the database side, we have time, date and timestamp (both time and date), possibly wi...

Install node modules npm install express npm install socket.io Node.js server const express = require('express'); const app = express(); const server = app.listen(3000,console.log("Socket.io Hello World server started!")); const io = require('socket.io')(server); io.on('connec...

Although this works only for WebKit based browsers, this is helpful: /* ----------- Non-Retina Screens ----------- */ @media screen and (min-width: 1200px) and (max-width: 1600px) and (-webkit-min-device-pixel-ratio: 1) { } /* ----------- Retina Screens ----------- */ @media scre...

When an object is exposed to the template context, its arguments-less methods are available. This is useful when these functions are "getters". But it can be hazardeous if these methods alter some data or have some side effects. Eventhough you likely trust the template writer, he may not b...

Classes have a local scope during definition, but functions inside the class do not use that scope when looking up names. Because lambdas are functions, and comprehensions are implemented using function scope, this can lead to some surprising behavior. a = 'global' class Fred: a = 'class' ...

When working with large files, you can use the System.IO.File.ReadLines method to read all lines from a file into an IEnumerable<string>. This is similar to System.IO.File.ReadAllLines, except that it doesn't load the whole file into memory at once, making it more efficient when working with l...

Ada 2012(TC-1) with Ada.Text_IO; procedure Main is type Fruit is (Banana, Orange, Pear); X : Fruit := Orange; begin Ada.Text_IO.Put_Line (X'Image); Ada.Text_IO.Put_Line (Pear'Image); end Main; Result ORANGE PEAR

Overridable Allows a property or method in a class to be overridden in a derived class. Public Class Person Public Overridable Sub DoSomething() Console.WriteLine("Person") End Sub End Class Overrides Overrides an Overridable property or method defined in the base...

Me uses the current object instance. MyClass uses the memberdefinition in the class where the member is called Class Person Public Overridable Sub DoSomething() Console.WriteLine("Person") End Sub Public Sub useMe() Me.DoSomething() End Sub ...

In Normal, type the following to delete a range of lines into a named register :10,20d a This will delete lines 10,20 in register "a. We can verify this by typing :reg This will show the text that was delete in register "a. To paste the contents in "a, just type "ap ...

0.18.0 Model is passed to subscriptions which means that every state change can modify subscriptions. import Html exposing ( Html, div, text, button ) import Html.Events exposing ( onClick ) import Time main : Program Never Model Msg main = Html.program { init = init ,...

Components define their own Messages, sent after emitted DOM Events, eg. CounterMsg from Parent-child communication type CounterMsg = Increment | Decrement | Reset The view of this component will send messages of CounterMsg type, therefore the view type signature is Html CounterMs...

In assignments, you can split an Iterable into values using the "unpacking" syntax: Destructuring as values a, b = (1, 2) print(a) # Prints: 1 print(b) # Prints: 2 If you try to unpack more than the length of the iterable, you'll get an error: a, b, c = [1] # Raises: ValueError:...

In functions, you can define a number of mandatory arguments: def fun1(arg1, arg2, arg3): return (arg1,arg2,arg3) which will make the function callable only when the three arguments are given: fun1(1, 2, 3) and you can define the arguments as optional, by using default values: def fun...

When you want to create a function that can accept any number of arguments, and not enforce the position or the name of the argument at "compile" time, it's possible and here's how: def fun1(*args, **kwargs): print(args, kwargs) The *args and **kwargs parameters are special parame...

switch statements are useful when you want to have your program do many different things according to the value of a particular test variable. An example usage of switch statement is like this: int a = 1; switch (a) { case 1: puts("a is 1"); break; case 2: puts("...

private final OkHttpClient client = new OkHttpClient(); public void run() throws Exception { RequestBody formBody = new FormBody.Builder() .add("search", "Jurassic Park") .build(); Request request = new Request.Builder() .url("https:...

with Ada.Text_IO; procedure Main is type Fruit is (Banana, Orange, Pear); X : Fruit := Orange; begin Ada.Text_IO.Put_Line (Fruit'Image (X)); end Main; Result ORANGE

You can find the Chef documentation at https://docs.chef.io/.