Tutorial by Examples: e

prop_evenNumberPlusOneIsOdd :: Integer -> Property prop_evenNumberPlusOneIsOdd x = even x ==> odd (x + 1) If you want to check that a property holds given that a precondition holds, you can use the ==> operator. Note that if it's very unlikely for arbitrary inputs to match the precondit...

A try/catch block is used to catch exceptions. The code in the try section is the code that may throw an exception, and the code in the catch clause(s) handles the exception. #include <iostream> #include <string> #include <stdexcept> int main() { std::string str("foo&...

One can iterate over a list using ~{ and ~} directives. CL-USER> (format t "~{~a, ~}~%" '(1 2 3 4 5)) 1, 2, 3, 4, 5, ~^ can be used to escape if there are no more elements left. CL-USER> (format t "~{~a~^, ~}~%" '(1 2 3 4 5)) 1, 2, 3, 4, 5 A numeric argument can ...

Google maintains documentation on getting started here: https://cloud.google.com/storage/docs/quickstart-console Getting ready to use GCS: Create a Google Cloud project, if you don't have one already. Enable billing for your project to allow buckets to be created. (Optional) Install the Google...

You can make an UILabel with a dynamic height using auto layout. You need to set the numberOfLines to zero (0), and add a minimal height by setting up a constraints with a relation of type .GreaterThanOrEqual on the .Height attribute iOS 6 Swift label.numberOfLines = 0 let heightConstraint = ...

Assumptions: An Oracle JDK has been installed. The JDK was installed to the default directory. Setup steps Open Windows Explorer. In the navigation pane on the left right click on This PC (or Computer for older Windows versions). There is a shorter way without using the explorer in...

Array iteration comes in two flavors, foreach and the classic for-loop: a=(1 2 3 4) # foreach loop for y in "${a[@]}"; do # act on $y echo "$y" done # classic for-loop for ((idx=0; idx < ${#a[@]}; ++idx)); do # act on ${a[$idx]} echo "${a[$idx]}&...

The recommended way (Since ES5) is to use Array.prototype.find: let people = [ { name: "bob" }, { name: "john" } ]; let bob = people.find(person => person.name === "bob"); // Or, more verbose let bob = people.find(function(person) { return person.na...

Ruby extends the standard group syntax (...) with a named group, (?<name>...). This allows for extraction by name instead of having to count how many groups you have. name_reg = /h(i|ello), my name is (?<name>.*)/i #i means case insensitive name_input = "Hi, my name is Zaphod Be...

Common mobile-optimized sites use the <meta name="viewport"> tag like this: <meta name="viewport" content="width=device-width, initial-scale=1"> The viewport element gives the browser instructions on how to control the page's dimensions and scaling based...

Syntax {condition-to-evaluate} ? {statement-executed-on-true} : {statement-executed-on-false} As shown in the syntax, the Conditional Operator (also known as the Ternary Operator1) uses the ? (question mark) and : (colon) characters to enable a conditional expression of two possible outcomes. It c...

To make express web application modular use router factories: Module: // greet.js const express = require('express'); module.exports = function(options = {}) { // Router factory const router = express.Router(); router.get('/greet', (req, res, next) => { res.end(options....

You can use the reversed function which returns an iterator to the reversed list: In [3]: rev = reversed(numbers) In [4]: rev Out[4]: [9, 8, 7, 6, 5, 4, 3, 2, 1] Note that the list "numbers" remains unchanged by this operation, and remains in the same order it was originally. To r...

After receiving the arguments, you can print them as follows: int main(int argc, char **argv) { for (int i = 1; i < argc; i++) { printf("Argument %d: [%s]\n", i, argv[i]); } } Notes The argv parameter can be also defined as char *argv[]. argv[0] may co...

Selenium Grid Node configuration resides on the Node itself and holds the information about network configuration and Node capabilities. The configuration can be applied in various ways: Default Configuration JSON Configuration Command line Configuration JSON Configuration The node configur...

Create a receiver. This class will receive the intent and handle it how you wish. public class AlarmReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { // Handle intent int reqCode = intent.getExtras().getInt(&...

Good for quick notifications that don't require interaction. Swift let alert = UIAlertController(title: "Toast", message: "Hello World", preferredStyle: .Alert) presentViewController(alert, animated: true) { let delay_s:Double = 2 let delayTime = dispatch_time(DI...

The data.table package introduces the function fread. While it is similar to read.table, fread is usually faster and more flexible, guessing the file's delimiter automatically. # get the file path of a CSV included in R's utils package csv_path <- system.file("misc", "exDIF.csv&q...

Create a XIB file Xcode Menu Bar > File > New > File. Select iOS, User Interface and then "View": Give your XIB a name (yes, we are doing a Pokemon example 👾). Remember to check your target and hit "Create". Design your view To make things easier, set:...

There are several R packages to read excel files, each of which using different languages or resources, as summarized in the following table: R packageUsesxlsxJavaXLconnectJavaopenxlsxC++readxlC++RODBCODBCgdataPerl For the packages that use Java or ODBC it is important to know details about your s...