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Immediately invoked function expressions may be written in a number of different ways. [3] A common convention is to enclose the function expression – and optionally its invocation operator – with the grouping operator, [4] in parentheses, to tell the parser explicitly to expect an expression.
The map function originated in functional programming languages. The language Lisp introduced a map function called maplist [3] in 1959, with slightly different versions already appearing in 1958. [4] This is the original definition for maplist, mapping a function over successive rest lists:
In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert ...
The C++ Standard Library's associative containers (std::unordered_map and std::map) use operator[] to get the value associated to a key. If there is nothing associated to this key, it will construct it and value initialize [4] [unreliable source] [failed verification] the value. For simple types like int or float, the value initialization will ...
A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored. A map implemented by a hash table is called a hash map.
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
Type inference on the map function proceeds as follows. map is a function of two arguments, so its type is constrained to be of the form a-> b-> c. In Haskell, the patterns [] and (first: rest) always match lists, so the second argument must be a list type: b = [d] for some type d.
The nested function technology allows a programmer to write source code that includes beneficial attributes such as information hiding, encapsulation and decomposition.The programmer can divide a task into subtasks which are only meaningful within the context of the task such that the subtask functions are hidden from callers that are not designed to use them.