Tutorial by Examples: en

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...

A container will stop if no command is running on the foreground. Using the -t option will keep the container from stopping, even when detached with the -d option. docker run -t -d debian bash

eof returns true only after reading the end of file. It does NOT indicate that the next read will be the end of stream. while (!f.eof()) { // Everything is OK f >> buffer; // What if *only* now the eof / fail bit is set? /* Use `buffer` */ } You could correctly write: ...

You can specify different dependencies for each platforms: "net45": { "frameworkAssemblies": { "System.Linq": "4.1.0" } }, "netstandard1.3": { "dependencies": { "NETStandard.Library": "1.6....

Using c# or vb.net code the conversion is even more simple. An output column is needed because we type can not be changed on the fly, alternative is adding an input column on forehand make it ReadWrite. Next code will fill the new column. public override void Input0_ProcessInputRow(Input0Buffer ...

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' ...

Extended asm support in gcc has the following syntax: asm [volatile] ( AssemblerTemplate : OutputOperands [ : InputOperands [ : Clobbers ] ]) asm [volatile] goto ( AssemblerTemplate : : Inp...

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

SQL has various join types to specify whether (non-)matching rows are included in the result: INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, and FULL OUTER JOIN (the INNER and OUTER keywords are optional). The figure below underlines the differences between these types of joins: the blue area repres...

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 ,...

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("...

To open a new window, add the following code somewhere where you can keep a reference to the new window (I.E., the app delegate). Swift let storyboard:NSStoryboard = NSStoryboard(name: "Main", bundle: nil) guard let controller:NSWindowController = storyboard.instantiateControllerWithIde...

If the type on which the static constructor is declared is generic, the static constructor will be called once for each unique combination of generic arguments. class Animal<T> { static Animal() { Console.WriteLine(typeof(T).FullName); } public static void Yawn...

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