Functional data structures are special forms of data structure, which are implemented primarily in functional programming languages. R supports functional programming by providing tools for creation and manipulation of functions. For example, R support assigning functions to variables and passing them as an argument within a function. The R support generating the function dynamically and returning them as a result of the function is also known as a closure function. For example, the function which takes a function as an argument is shown as follows:
arg_function <- function(g) g(seq(1, 100, by=1))
The function arg_function can take functions as an argument, such as mean or sd as shown in the following code snippet:
> arg_function(mean) [1] 50.5 > arg_function(sd) [1] 29.01149
The functional data structure is also known as persistent data structure as they are immutable in the sense that any operation performed on function data structure will create a new...