Tutorial by Examples: ti

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...

Only the homepage works, all other pages return 404 Make sure mod_rewrite module has been installed in Apache and been enabled to load. See step 2 for info on how to do this here: https://www.digitalocean.com/community/tutorials/how-to-set-up-mod_rewrite-for-apache-on-ubuntu-14-04 Make sure the y...

Profiling string concatanation: In [1]: import string In [2]: %%timeit s=""; long_list=list(string.ascii_letters)*50 ....: for substring in long_list: ....: s+=substring ....: 1000 loops, best of 3: 570 us per loop In [3]: %%timeit long_list=list(string.ascii_letters)*50...

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

Profiling concatanation of numbers python -m timeit "'-'.join(str(n) for n in range(100))" 10000 loops, best of 3: 29.2 usec per loop python -m timeit "'-'.join(map(str,range(100)))" 100000 loops, best of 3: 19.4 usec per loop

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...

Sometimes we need to make a lot of POST requests to one or many different endpoints. To deal with this scenario, we can use multi_curl. First of all, we create how many requests as needed exactly in the same way of the simple example and put them in an array. We use the curl_multi_init and add eac...

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...

Assertations mean that a condition should be checked and if it's false, it's an error. For static_assert(), this is done compile-time. template<typename T> T mul10(const T t) { static_assert( std::is_integral<T>::value, "mul10() only works for integral types" ); re...

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:...

You can add subscripting to your own classes by implementing the required methods. For indexed subscripting (like arrays): - (id)objectAtIndexedSubscript:(NSUInteger)idx - (void)setObject:(id)obj atIndexedSubscript:(NSUInteger)idx For keyed subscripting (like dictionaries): - (id)objectForKey...

the steps in this example will use the following project structure as a demonstration and we intend to export it to the "GHTuts" Repository [Note that the Repo doesn't exist yet on github] but leave the "SensitiveProject" without publish as it contains some passwords, keys, et...

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...

The common idiom for loading shared library files in Java is the following : public class ClassWithNativeMethods { static { System.loadLibrary("Example"); } public native void someNativeMethod(String arg); ... Calls to System.loadLibrary are almost always...

Quite often you have a file which was edited within DOS or Windows and you are viewing it under UNIX. This can look like the following when you view the file with vi. First line of file^M Next Line^M And another^M If you wish to remove the ^M, it can be that you delete each ^M by hand. Alter...

Timers are used to perform tasks at specific intervals of time (Do X every Y seconds) Below is an example of creating a new instance of a Timer. NOTE: This applies to Timers using WinForms. If using WPF, you may want to look into DispatcherTimer using System.Windows.Forms; //Timers use the Wi...

All actions performed in a timer are handled in the "Tick" event. public partial class Form1 : Form { Timer myTimer = new Timer(); public Form1() { InitializeComponent(); myTimer.Tick += myTimer_Tick; //assign the event handler named "myT...

public partial class Form1 : Form { Timer myTimer = new Timer(); int timeLeft = 10; public Form1() { InitializeComponent(); //set properties for the Timer myTimer.Interval = 1000; myTimer.Enabled = tru...

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...