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iex> ~w(a b c)a [:a, :b, :c]

git diff HEAD^ HEAD This will show the changes between the previous commit and the current commit.

instance Monoid [a] where mempty = [] mappend = (++) Checking the Monoid laws for this instance: mempty `mappend` x = x <-> [] ++ xs = xs -- prepending an empty list is a no-op x `mappend` mempty = x <-> xs ++ [] = xs -- appending an empty list is a no-op x...

mconcat :: [a] -> a is another method of the Monoid typeclass: ghci> mconcat [Sum 1, Sum 2, Sum 3] Sum {getSum = 6} ghci> mconcat ["concat", "enate"] "concatenate" Its default definition is mconcat = foldr mappend mempty.

By default, user input history in IEx do not persist across different sessions. erlang-history adds history support to both the Erlang shell and IEx: git clone [email protected]:ferd/erlang-history.git cd erlang-history sudo make install You can now access your previous inputs using the up and d...

If you do not require an array to be in any particular order, a little trick with pop() will afford you enormous performance gains compared to splice(). When you splice() an array, the index of subsequent elements in that array needs to be reduced by 1. This process can consume a large chunk of tim...

Create function in MyComponent.php namespace app\components; use Yii; use yii\base\Component; use yii\base\InvalidConfigException; use yii\helpers\Url; use yii\helpers\ArrayHelper; use app\models\User; class MyComponent extends Component ...

New or detached objects may be added to the session using add(): session.add(obj) A sequence of objects may be added using add_all(): session.add_all([obj1, obj2, obj3]) An INSERT will be emitted to the database during the next flush, which happens automatically. Changes are persisted when t...

To delete persisted objects use delete(): session.delete(obj) Actual deletion from the database will happen on next flush.

Implementing the IEnumerable interface allows classes to be enumerated in the same way as BCL collections. This requires extending the Enumerator class which tracks the state of the enumeration. Other than iterating over a standard collection, examples include: Using ranges of numbers based on a...

The <algorithm> header provides a number of useful functions for working with sorted vectors. An important prerequisite for working with sorted vectors is that the stored values are comparable with <. An unsorted vector can be sorted by using the function std::sort(): std::vector<int&...

Note: it's strongly advised to use Composer. The instruction below is basically what Composer does for you. Download archive extension file of needed version from Github Open composer.json Find PSR-4 autoload section and remember it for e.g. kmit/select2 Extract files to corresponding fold...

() is a Monoid. Since there is only one value of type (), there's only one thing mempty and mappend could do: instance Monoid () where mempty = () () `mappend` () = ()

public class Customer { public void SendEmail() { // Sending email code here } } List<Customer> customers = new List<Customer>(); customers.Add(new Customer()); customers.Add(new Customer()); customers.ForEach(c => c.SendEmail());

Install Codeception: composer global status composer global require "codeception/codeception=~2.0.0" "codeception/specify=*" "codeception/verify=*" Install Faker: cd /var/www/yii // Path to your application composer require --de...

If you need to count distinct characters then, for the reasons explained in Remarks section, you can't simply use Length property because it's the length of the array of System.Char which are not characters but code-units (not Unicode code-points nor graphemes). If, for example, you simply write tex...

We cannot break a string into arbitrary points (because a System.Char may not be valid alone because it's a combining character or part of a surrogate) then code must take that into account (note that with length I mean the number of graphemes not the number of code-units): public static IEnumerabl...

.NET strings contain System.Char (UTF-16 code-units). If you want to save (or manage) text with another encoding you have to work with an array of System.Byte. Conversions are performed by classes derived from System.Text.Encoder and System.Text.Decoder which, together, can convert to/from another ...

There is no need to create the whole UI in a single FXML using a single controller. The <fx:include> tag can be used to include one fxml file into another. The controller of the included fxml can be injected into the controller of the including file just as any other object created by the FXM...

If there are no specific needs, choose x86_64 system images with Google APIs to create the emulator. It works way faster than armeabi-v7a on intel x86 x64 based computers. There are some SDK libraries compiled and designed with ARM architecture. If you try to install them on Intel based emulators...