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In programming languages (especially functional programming languages) and type theory, an option type or maybe type is a polymorphic type that represents encapsulation of an optional value; e.g., it is used as the return type of functions which may or may not return a meaningful value when they are applied.
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type.In statically typed languages, a nullable type is an option type, [citation needed] while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null ...
In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".
In object-oriented programming, the safe navigation operator (also known as optional chaining operator, safe call operator, null-conditional operator, null-propagation operator) is a binary operator that returns null if its first argument is null; otherwise it performs a dereferencing operation as specified by the second argument (typically an ...
The date and time that the message was sent (in "HTTP-date" format as defined by RFC 9110) Date: Tue, 15 Nov 1994 08:12:31 GMT: Permanent RFC 9110: Delta-Base: Specifies the delta-encoding entity tag of the response. [11] Delta-Base: "abc" Permanent RFC 3229: ETag: An identifier for a specific version of a resource, often a message digest
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types ...
Valhalla is incubating Java language features and enhancements in these areas: [2] [3] Value Classes and Objects: highly-efficient objects without their own identity (reference value). Null-restricted and Nullable types, and Null-restricted Objects: for example, using ? or ! after type declaration to say if null is allowed or not.
Without named parameters, optional parameters can only appear at the end of the parameter list, since there is no other way to determine which values have been omitted. In languages that support named optional parameters, however, programs may supply any subset of the available parameters, and the names are used to determine which values have ...