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In an object-oriented programming language such as Java versions before function-valued arguments, the behavior of a callback can be achieved by passing an object that implements an interface. The methods of this object are callbacks.
In a programming language, an evaluation strategy is a set of rules for evaluating expressions. [1] The term is often used to refer to the more specific notion of a parameter-passing strategy [2] that defines the kind of value that is passed to the function for each parameter (the binding strategy) [3] and whether to evaluate the parameters of a function call, and if so in what order (the ...
Conversely, in an eager language the above definition for ifThenElse a b c would evaluate (a), (b), and (c) regardless of the value of (a). This is not the desired behavior, as (b) or (c) may have side effects, take a long time to compute, or throw errors. It is usually possible to introduce user-defined lazy control structures in eager ...
A higher-order function is a function that takes a function as an argument or returns one as a result. This is commonly used to customize the behavior of a generically defined function, often a looping construct or recursion scheme. Anonymous functions are a convenient way to specify such function arguments. The following examples are in Python 3.
Replace each free variable with an additional argument to the enclosing function, and pass that argument to every use of the function. Replace every local function definition that has no free variables with an identical global function. Repeat steps 2 and 3 until all free variables and local functions are eliminated.
Calling f with a regular function argument first applies this function to the value 2, then returns 3. However, when f is passed to call/cc (as in the last line of the example), applying the parameter (the continuation) to 2 forces execution of the program to jump to the point where call/cc was called, and causes call/cc to return the value 2.
This property is inherited from lambda calculus, where multi-argument functions are usually represented in curried form. Currying is related to, but not the same as partial application . [ 1 ] [ 2 ] In practice, the programming technique of closures can be used to perform partial application and a kind of currying, by hiding arguments in an ...
Python sets are very much like mathematical sets, and support operations like set intersection and union. Python also features a frozenset class for immutable sets, see Collection types. Dictionaries (class dict) are mutable mappings tying keys and corresponding values. Python has special syntax to create dictionaries ({key: value})