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In C++, the std::map class is templated which allows the data types of keys and values to be different for different map instances. For a given instance of the map class the keys must be of the same base type. The same must be true for all of the values.
Aside from the seven "primitive" data types, every value in JavaScript is an object. [49] ECMAScript 2015 also added the Map data structure, which accepts arbitrary values as keys. [50] C++11 includes unordered_map in its standard library for storing keys and values of arbitrary types. [51] Go's built-in map implements a hash table in the form ...
A UML class diagram for a strongly typed identifier. A strongly typed identifier is user-defined data type which serves as an identifier or key that is strongly typed. This is a solution to the "primitive obsession" code smell as mentioned by Martin Fowler. The data type should preferably be immutable if possible.
returns a function or value as its result. All other functions are first-order functions. In mathematics higher-order functions are also termed operators or functionals. The differential operator in calculus is a common example, since it maps a function to its derivative, also a function.
In Haskell, the polymorphic function map :: (a -> b) -> [a] -> [b] is generalized to a polytypic function fmap :: Functor f => (a -> b) -> f a -> f b, which applies to any type belonging the Functor type class. The type constructor of lists [] can be defined as an instance of the Functor type class using the map function from the previous example:
Number and String The string is converted to a number value. JavaScript attempts to convert the string numeric literal to a Number type value. First, a mathematical value is derived from the string numeric literal. Next, this value is rounded to nearest Number type value. Boolean
Many languages provide a built-in string data type, with specialized notation ("string literals") to build values of that type. In some languages (such as C), a string is just an array of characters, or is handled in much the same way. Other languages, like Pascal, may provide vastly different operations for strings and arrays.
Another example in JavaScript uses the built-in methods of Array: filter somethings . filter ( x => x . count > 10 ) . sort (( a , b ) => a . count - b . count ) . map ( x => x . name ) Note that in JavaScript filter and map return a new shallow copy of the preceding array but sort operates in place.