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Maybe Maybe is a Functor containing a possibly-absent value: instance Functor Maybe where fmap f Nothing = Nothing fmap f (Just x) = Just (f x) Maybe's instance of Functor applies a function to a value wrapped in a Just. If the computation has previously failed (so the Maybe value is ...

The __import__() function can be used to import modules where the name is only known at runtime if user_input == "os": os = __import__("os") # equivalent to import os This function can also be used to specify the file path to a module mod = __import__(r"C:/path/...

A VHDL program can be simulated or synthesized. Simulation is what resembles most the execution in other programming languages. Synthesis translates a VHDL program into a network of logic gates. Many VHDL simulation and synthesis tools are parts of commercial Electronic Design Automation (EDA) s...

docker run --add-host="app-backend:10.15.1.24" awesome-app This command adds an entry to the container's /etc/hosts file, which follows the format --add-host <name>:<address>. In this example, the name app-backend will resolve to 10.15.1.24. This is particularly useful for t...

Conditions are a fundamental part of almost any part of code. They are used to execute some parts of the code only in some situations, but not other. Let's look at the basic syntax: a = 5; if a > 10 % this condition is not fulfilled, so nothing will happen disp('OK') end if a < 1...

In some cases we want to run an alternative code if the condition is false, for this we use the optional else part: a = 20; if a < 10 disp('a smaller than 10') else disp('a bigger than 10') end Here we see that because a is not smaller than 10 the second part of the code, after t...

/** * @param num Numerator * @param denom Denominator * @throws ArithmeticException in case `denom` is `0` */ class Division @throws[ArithmeticException](/*no annotation parameters*/) protected (num: Int, denom: Int) { private[this] val wrongValue = num / denom /** Integer n...

This simple macro annotation outputs the annotated item as-is. import scala.annotation.{compileTimeOnly, StaticAnnotation} import scala.reflect.macros.whitebox.Context @compileTimeOnly("enable macro paradise to expand macro annotations") class noop extends StaticAnnotation { def m...

C++14 Those following duration user literals are declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces. Access to these operators can be gained with using namespace std::literals, using namespace std::chrono_literals, and using names...

A const Enum is the same as a normal Enum. Except that no Object is generated at compile time. Instead, the literal values are substituted where the const Enum is used. // Typescript: A const Enum can be defined like a normal Enum (with start value, specifig values, etc.) const enum NinjaActivity ...

You may have noticed that many applications have double-back-click functionality to exit the app. In this example, we are overriding the default back button action using the onBackPressed() method override. This method will Toast a message for the single back-click action, and will close the app if...

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...

First, Install Java SE Development Kit This can be as simple as downloading, double-clicking on the downloaded file, and following the installation instructions. For install Java SE Development Kit download it from official web site. Java SE Development Kit. Downloads After JDK install is complete...

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

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...

Anonymous classes were introduced into PHP 7 to enable for quick one-off objects to be easily created. They can take constructor arguments, extend other classes, implement interfaces, and use traits just like normal classes can. In its most basic form, an anonymous class looks like the following: ...