Full Answer
What is the type option in Scala?
After mastering high order functions, you’re going to learn about the type Option. In Scala, using null to represent nullable or missing values is an anti-pattern: use the type Option instead. The type Option ensures that you deal with both the presence and the absence of an element.
What is the use of some and none in Scala?
This some and none are part of Scala Option that searches for the key and returns the value if it founds that and none is returned if it doesn’t find the value. So here it uses the Scala Option to fetch the value and handle none. It can be best use when we have to implement the Scala Pattern Matching.
What is the use of null in Scala?
In Scala, using null to represent nullable or missing values is an anti-pattern: use the type Option instead. The type Option ensures that you deal with both the presence and the absence of an element. Thanks to the Option type, you can make your system safer by avoiding nasty NullPointerException s at runtime.
Why does Scala use a for type parameters?
Scala has a convention of using upper case letters of the alphabet for type parameters, the reason why Option uses A, but you could provide any other name for it. case class Some [A] (a: A) extends Option [A] Some is case class and a valid implementation of Option that represents the presence of a value.
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What does option in Scala mean?
The Option in Scala is referred to a carrier of single or no element for a stated type. When a method returns a value which can even be null then Option is utilized i.e, the method defined returns an instance of an Option, in place of returning a single object or a null.
What is an option string?
The STRING option in GET and PUT statements transmits data between main storage locations rather than between the main and a data set.
Is Scala option a collection?
Option can be seen as a collection that has zero or exactly one element, and it provides a degree of interoperability with the collection types found in the package scala.
Which are the forms of the option class in Scala?
filter – Returns the Option if the Option's value is Some and the supplied function returns true. filterNot – Returns the Option if the Option's value is Some and the supplied function returns false. exists – Returns true if the Option is set and the supplied function returns true.
Can options be null Scala?
In Scala, using null to represent nullable or missing values is an anti-pattern: use the type Option instead. The type Option ensures that you deal with both the presence and the absence of an element. Thanks to the Option type, you can make your system safer by avoiding nasty NullPointerException s at runtime.
What is null in Scala?
Null is - together with scala. Nothing - at the bottom of the Scala type hierarchy. Null is the type of the null literal. It is a subtype of every type except those of value classes. Value classes are subclasses of AnyVal, which includes primitive types such as Int, Boolean, and user-defined value classes.
What is collections in Scala?
Scala has a rich set of collection library. Collections are containers of things. Those containers can be sequenced, linear sets of items like List, Tuple, Option, Map, etc. The collections may have an arbitrary number of elements or be bounded to zero or one element (e.g., Option).
What is flatMap in Scala?
In Scala, the function flatMap is a high order function on Option[A] that applies a function f , which returns an optional value itself – in other words, f has type A => Option[B] : If the optional value is present, it applies the function f to it.
What is flatten in Scala?
flatten() method is a member GenericTraversableTemplate trait, it returns a single collection of elements by merging child collections.
What is a tuple in Scala?
In Scala, a tuple is a value that contains a fixed number of elements, each with its own type. Tuples are immutable. Tuples are especially handy for returning multiple values from a method.
What is try in Scala?
The Try type represents a computation that may either result in an exception, or return a successfully computed value. It's similar to, but semantically different from the scala. util. Either type. Instances of Try[T] , are either an instance of scala.
What is fold in Scala?
The fold function is applicable to both Scala's Mutable and Immutable collection data structures. The fold method takes an associative binary operator function as parameter and will use it to collapse elements from the collection. The fold method allows you to also specify an initial value.
What is the difference between an option and a share?
The biggest difference between options and stocks is that stocks represent shares of ownership in individual companies, while options are contracts with other investors that let you bet on which direction you think a stock price is headed.
What is an option letter?
Option Letter means a written or electronic letter agreement between the Company and an Optionee evidencing the terms and conditions of an individual Option grant. An Option Letter is subject to the terms and conditions of the Plan.
How do you read an option ticker?
In an option ticker, it is represented right after the expiration date. If the contract is a call option, it is represented by a “C”. If it is a put option, it is represented by a “P”. So for example, a MSFT call option that expires on October 8th, 2021, would begin with “MSFT211008C”.
How do you read an option title?
The components of an options symbol are: Root symbol (ticker symbol) + Expiration Year (yy) + Expiration Month (mm) + Expiration Day (dd) + Call/Put Indicator (C or P) + Strike Price*.
What is option type in Scala?
Option type is used frequently in Scala programs and you can compare this with the null value available in Java which indicate no value. For example, the get method of java.util.HashMap returns either a value stored in the HashMap, or null if no value was found.
What is a T in Scala?
Scala Option [ T ] is a container for zero or one element of a given type. An Option [T] can be either Some [T] or None object, which represents a missing value. For instance, the get method of Scala's Map produces Some (value) if a value corresponding to a given key has been found, or None if the given key is not defined in the Map.
How to take optional values apart?
The most common way to take optional values apart is through a pattern match. For example try the following program.
What does return this option do?
Returns this Option if it is nonempty, otherwise return the result of evaluating alternative.
What is a scala option?
Scala Option checks the return type of the method and returns the value with the some class if there is a value returned or else none is returned for a null value. Whenever a null is returned over a normal function and when it is not handled with in the program we are most liable to get an error of NULLpointerException, but with the help of option over the scala code we will not get this Null pointer Exception. It is better used with Match function.
What is some and none in Scala?
This some and none are part of Scala Option that searches for the key and returns the value if it founds that and none is returned if it doesn’t find the value. So here it uses the Scala Option to fetch the value and handle none.
What does the get or else method do?
The get or else method will check if it has some value and return accordingly.
What is Scala option?
A Scala Option holds zero or one element of a type. This means that it is either a Some [T] or a none object. One place we get an Option value is through the get () method for a Map.
What happens if the Scala option satisfies the predicate?
If the Scala Option’s value satisfies the predicate, this returns that value.
What happens if Scala is not available?
If the Scala Option is None, this returns true; otherwise, it returns false.
What does "if option is an instance of some" mean?
If the Option is an instance of Some, this returns true; otherwise, false.
What happens if the option's value does not satisfy the predicate?
If the Option’s value does not satisfy the predicate, this returns that value.
What happens when an option has a value?
If the Option has a value, this applies the function to that value, and then returns it.
What is an option in Scala?
sealed abstract class Option [A] Option is an abstract class, and you can’t initialize it directly.
Why does Scala use A?
Scala has a convention of using upper case letters of the alphabet for type parameters, the reason why Option uses A, but you could provide any other name for it. case class Some [A] (a: A) extends Option [A] Some is case class and a valid implementation of Option that represents the presence of a value.
What is the difference between "nothing" and "null" in Scala?
The terms None, Nothing and null can get confusing here; let’s recap what each of them means. None is an instance of the class Option, and it represents a missing nullable value. Nothing is a type that you can associate with all other Scala types. The term null is a keyword of the language to indicate a missing reference to an object.
What is Scala notation for generics?
An optional type works independently from the value it contains: you would expect an optional value to work in the same way of an optional integer, an optional string or any other optional value.
What is type option?
The type Option is equivalent to a wrapper around your value to provide the essential information that it may be missing. Thanks to the use of Option, you no longer need to look at the specific implementation of a function to discover if its return value is nullable: this information is in its signature. The compiler also makes sure that you handle both the cases when it’s present and when it’s absent, making your application safer at runtime.
Can you reimplement a sqrt function?
You can now re-implement your sqrt function to use the type Option as shown in listing 2:
Is any a subclass?
Any is the superclass of every other class —it’s the root of the class hierarchy. Nothing is at the bottom of the class hierarchy —it’s the subclass of every other class. Because None extends Option [Nothing], you can use None as a valid implementation for Option independently of its type parameter.
Why can you create a class without new in Scala?
So a possibility to create an object of this class without new is because there is a method apply in "default" companion object.
What is a factory method in Scala?
A "factory method" is usually a static method that constructs the value of some type, possibly hiding the details of the type itself. In this case fromString is a factory method because it allows you create an Email without calling the Email constructor with new Email (...)
What is option in email?
About Option, it provides you a possibility to avoid some exception and make something when you don't have any values. Gabriele put an example with email, so I'll add another one. You have a method that sends email, but you take email from User class. The user can have this field empty, so if we have something like it val maybeEmail: Option [String] = user.email you can use for example map to send an email maybeEmail.map (email => sendEmail (email))
What is an option in a data structure?
Option is a data structure that represents optionality, as the name suggests . Whenever a computation may not return a value, you can return an Option. Option has two cases (represented as two subclasses): Some or None.
Is match a way to work with option?
Also, note that using match is just a way of working with Option . Further discussion would involve using map, flatMap, getOrElse or similar methods defined on Option, but I feel it would be off-topic here.
What does scala.option return?
Returns the option's value if it is nonempty, or null if it is empty. Although the use of null is discouraged, code written to use scala.Option must often interface with code that expects and returns nulls. A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.
What is an instance of option?
Represents optional values. Instances of Option are either an instance of scala.Some or the object None.
How to build a new iterable collection?
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
What operator is used to fold the elements of this iterable collection?
Folds the elements of this iterable collection using the specified associative binary operator.
How does a partial function build a new iterable collection?
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Can Scala.Option be chained?
This allows for sophisticated chaining of scala.Option values without having to check for the existence of a value.
Can you wrap a null in Scala?
Interacting with code that can occasionally return null can be safely wrapped in scala.Option to become None and scala.Some otherwise.
