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In computer programming, a function object [a] is a construct allowing an object to be invoked or called as if it were an ordinary function, usually with the same syntax (a function parameter that can also be a function). In some languages, particularly C++, function objects are often called functors (not related to the functional programming ...
For example, one could define a dictionary having a string "toast" mapped to the integer 42 or vice versa. The keys in a dictionary must be of an immutable Python type, such as an integer or a string, because under the hood they are implemented via a hash function. This makes for much faster lookup times, but requires keys not change.
Like raw strings, there can be any number of equals signs between the square brackets, provided both the opening and closing tags have a matching number of equals signs; this allows nesting as long as nested block comments/raw strings use a different number of equals signs than their enclosing comment: --[[comment --[=[ nested comment ...
For function that manipulate strings, modern object-oriented languages, like C# and Java have immutable strings and return a copy (in newly allocated dynamic memory), while others, like C manipulate the original string unless the programmer copies data to a new string.
There are two types of divisions in Python: floor division (or integer division) // and floating-point / division. [103] Python uses the ** operator for exponentiation. Python uses the + operator for string concatenation. Python uses the * operator for duplicating a string a specified number of times.
This is called juxtaposition. Unix shells have a similar syntax. Rexx uses this syntax for concatenation including an intervening space. C (along with Python) allows juxtaposition for string literals, however, for strings stored as character arrays, the strcat function must be used. COBOL uses the STRING statement to concatenate string variables.
In C and C++, a callable unit is called a function. A function definition starts with the name of the type of value that it returns or void to indicate that it does not return a value. This is followed by the function name, formal arguments in parentheses, and body lines in braces.
Thus, calling f x, where f:: a-> b-> c, yields a new function f2:: b-> c that can be called f2 b to produce c. The actual type specifications can consist of an actual type, such as Integer, or a general type variable that is used in parametric polymorphic functions, such as a, or b, or anyType. So we can write something like: functionName:: a ...