Tutorial by Examples: io

Paramorphisms model primitive recursion. At each iteration of the fold, the folding function receives the subtree for further processing. para :: Functor f => (f (Fix f, a) -> a) -> Fix f -> a para f = f . fmap (\x -> (x, para f x)) . unFix The Prelude's tails can be modelled as ...

Apomorphisms model primitive corecursion. At each iteration of the unfold, the unfolding function may return either a new seed or a whole subtree. apo :: Functor f => (a -> f (Either (Fix f) a)) -> a -> Fix f apo f = Fix . fmap (either id (apo f)) . f Note that apo and para are dual...

Profiling repetition of elements in an array >>> import timeit >>> timeit.timeit('list(itertools.repeat("a", 100))', 'import itertools', number = 10000000) 10.997665435877963 >>> timeit.timeit('["a"]*100', number = 10000000) 7.118789926862576

Description An image maps is an image with clickable areas that usually act as hyperlinks. The image is defined by the <img> tag, and the map is defined by a <map> tag with <area> tags to denote each clickable area. Use the usemap and name attributes to bind the image and the map...

Just like most other C-style languages, each statement is terminated with a semicolon. Also, a closing tag is used to terminate the last line of code of the PHP block. If the last line of PHP code ends with a semicolon, the closing tag is optional if there is no code following that final line of co...

Subscripts can also be used with NSDictionary and NSMutableDictionary. The following code: NSMutableDictionary *myDictionary = [@{@"Foo": @"Bar"} mutableCopy]; [myDictionary setObject:@"Baz" forKey:@"Foo"]; NSLog(@"%@", [myDictionary objectForKey:...

In PCRE, matched groups used for backreferences before a recursion are kept in the recursion. But after the recursion they all reset to what they were before entering it. In other words, matched groups in the recursion are all forgotten. For example: (?J)(?(DEFINE)(\g{a}(?<a>b)\g{a}))(?<a...

In PCRE, it doesn't trackback after the first match for a recursion is found. So (?(DEFINE)(aaa|aa|a))(?1)ab doesn't match aab because after it matched aa in the recursion, it never try again to match only a.

Prerequisite steps: Install Java at your machine Visit neo4j website and click the link "Download Community Edition" or visit directly the download link. Unzip the .tar downloaded file in your home directory Start Neo4j from console (headless, without web server) Visit the sub-d...

My first Wicket setup, app showing Hello World on home screen: import org.apache.wicket.protocol.http.WebApplication; public class HelloWorldApplication extends WebApplication { public HelloWorldApplication() { } @Override public Class getHomePage() { retur...

class MyDataObject extends DataObject { ... private static $has_many = array( 'OtherDataObjects' => 'OtherDataObject' ); function getCMSFields() { $fields = parent::getCMSFields(); if ($gridField = $fields->dataFieldByName('OtherDataObject...

To check whether a value is a character use the is.character() function. To coerce a variable to a character use the as.character() function. x <- "The quick brown fox jumps over the lazy dog" class(x) [1] "character" is.character(x) [1] TRUE Note that numerics can be ...

In [1]: ser = pd.Series(['lORem ipSuM', 'Dolor sit amet', 'Consectetur Adipiscing Elit']) Convert all to uppercase: In [2]: ser.str.upper() Out[2]: 0 LOREM IPSUM 1 DOLOR SIT AMET 2 CONSECTETUR ADIPISCING ELIT dtype: object All lowercase: In [3]: ser...

You can think of an OperationQueue as a line of tasks waiting to be executed. Unlike dispatch queues in GCD, operation queues are not FIFO (first-in-first-out). Instead, they execute tasks as soon as they are ready to be executed, as long as there are enough system resources to allow for it. Get th...

The Foundation framework provides the Operation type, which represents a high-level object that encapsulates a portion of work that may be executed on a queue. Not only does the queue coordinate the performance of those operations, but you can also establish dependencies between operations, create c...

Java configuration is typically done by applying the @Configuration annotation to a class to suggest that a class contains bean definitions. The bean definitions are specified by applying the @Bean annotation to a method that returns an object. @Configuration // This annotation tells the Applicati...

Xml configuration is typically done by defining beans within an xml file, using Spring's specific beans schema. Under the root beans element, typical bean definition would be done using the bean subelement. <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="htt...

You can combine the results of two identically structured queries with the UNION keyword. For example, if you wanted a list of all contact info from two separate tables, authors and editors, for instance, you could use the UNION keyword like so: select name, email, phone_number from authors u...

A model represents some data object in an application. For example you can have a model such as: Fruit, Car, Building, etc. in your application. Models are normally used by stores. Here is example how you would define a new model class. e.g. Ext.define('MyApp.model.Person', { extend: 'Ext.data...

There are two ways to setup the Apache Flex SDK. You can use the provided Apache Flex SDK Installer, an Adobe AIR application that automates the process (on Windows or OS X/macOS). Or you can install it manually which obviously requires a greater comfort with your platform but provides more flexibi...