Tutorial by Examples: er

F# allows functions to be added as "members" to types when they are defined (for example, Record Types). However F# also allows new instance members to be added to existing types - even ones declared elsewhere and in other .net languages. The following example adds a new instance method D...

[<Measure>] type m // meters [<Measure>] type cm // centimeters // Conversion factor let cmInM = 100<cm/m> let distanceInM = 1<m> let distanceInCM = distanceInM * cmInM // 100<cm> // Conversion function let cmToM (x : int<cm>) = x / 100<cm/m> l...

Components have various parameters that can be set for them. They vary from component to component, so a good way to see what parameters can be set for components is to start typing componentName.set, and let your IDE's autocomplete (If you use an IDE) suggest methods. The default shortcut in many I...

Having a button there is all well and good, but what's the point if clicking it does nothing? ActionListeners are used to tell your button, or other component to do something when it is activated. Adding ActionListeners is done as such. buttonA.addActionListener(new ActionListener() { @Overri...

The following examples show 3 main methods for installing Erlang/OTP on FreeBSD. Method 1 - Pre-built Binary Package Use pkg to install the pre-built binary package: $ pkg install erlang Test your new installation: $ erl Erlang/OTP 18 [erts-7.3.1] [source] [64-bit] [smp:2:2] [async-threads:1...

Catamorphisms, or folds, model primitive recursion. cata tears down a fixpoint layer by layer, using an algebra function (or folding function) to process each layer. cata requires a Functor instance for the template type f. cata :: Functor f => (f a -> a) -> Fix f -> a cata f = f . fma...

Anamorphisms, or unfolds, model primitive corecursion. ana builds up a fixpoint layer by layer, using a coalgebra function (or unfolding function) to produce each new layer. ana requires a Functor instance for the template type f. ana :: Functor f => (a -> f a) -> a -> Fix f ana f = Fi...

INSERT INTO table_name (json_col) VALUES ('{"City": "Galle", "Description": "Best damn city in the world"}'); That's simple as it can get but note that because JSON dictionary keys have to be surrounded by double quotes the entire thing should b...

Cryptography is something very hard and after spending a lot of time reading different examples and seeing how easy it is to introduce some form of vulnerability I found an answer originally written by @jbtule that I think is very good. Enjoy reading: "The general best practice for symmetric e...

The List API has eight methods for positional access operations: add(T type) add(int index, T type) remove(Object o) remove(int index) get(int index) set(int index, E element) int indexOf(Object o) int lastIndexOf(Object o) So, if we have a List: List<String> strings = new ArrayL...

For the example, lets say that we have a List of type String that contains four elements: "hello, ", "how ", "are ", "you?" The best way to iterate over each element is by using a for-each loop: public void printEachElement(List<String> list){ for...

The implementation of INotifyPropertyChange can be error-prone, as the interface requires specifying property name as a string. In order to make the implementation more robust, an attribute CallerMemberName can be used. class C : INotifyPropertyChanged { // backing field int offset; ...

mysqladmin -u root -p'old-password' password 'new-password'

#include <iostream> long double operator"" _km(long double val) { return val * 1000.0; } long double operator"" _mi(long double val) { return val * 1609.344; } int main() { std::cout << "3 km = " << 3.0_km << " m...

Batch execution using java.sql.PreparedStatement allows you to execute a single DML statement with multiple sets of values for its parameters. This example demonstrates how to prepare an insert statement and use it to insert multiple rows in a batch. Connection connection = ...; // obtained earl...

The width and height attributes designate the dimensions of the rectangle. These values are in pixels by default The fill value sets the color for the rectangle. If no value for fill is specified, black is used by default <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="h...

If you use a dictionary as an iterator (e.g. in a for statement), it traverses the keys of the dictionary. For example: d = {'a': 1, 'b': 2, 'c':3} for key in d: print(key, d[key]) # c 3 # b 2 # a 1 The same is true when used in a comprehension print([key for key in d]) # ['c', 'b', '...

Throughout this example it is assumed that the 'root' object that is being serialized to JSON is an instance of the following class : public class MyJson { }   Example 1 : An example of an instance of MyJson, as is: {} i.e. since the class has no fields, only curly brackets are serialized...

Math.sin and Math.cos are cyclic with a period of 2*PI radians (360 deg) they output a wave with an amplitude of 2 in the range -1 to 1. Graph of sine and cosine function: (courtesy Wikipedia) They are both very handy for many types of periodic calculations, from creating sound waves, to animati...

In XAML: <RadioButton IsChecked="{Binding EntityValue, Mode=TwoWay, Converter={StaticResource StringToIsCheckedConverter}, ConverterParameter=Male}" Content="Male"/> <RadioButton IsChecked="{Bindi...