4.12: section 12: OOP and functional programming

Question 1

define function application

Answer 1

process of giving particular inputs to a function

Question 2

what is function type

Answer 2

f: A ->B

f = function
A = argument type: set of inputs =domain
B = result type
set of outputs = co-domain

A and B must be subsets of objects in some data type

Question 3

how many arguments can functions take

Answer 3

• although it seems multiple functions are being passed through only 1 is actually being applied
• instead the result and function are passed as inputs

Question 4

define partial function application

Answer 4

takes advantage of the inability of a function to take more than one input

-one of the arguments is fixed leading to a more restricted specialized function

Question 5

define composition functions

Answer 5

operation functional composition combines two functions to get a new function.

Question 6

what is a high order function

Answer 6

A function is higher-order if it takes a function as an argument or returns a function as a result, or does both.

Question 7

what is the map function

Answer 7

a higher-order function that applies a given function to each element of a list, returning a list of results.

Question 8

what is a filter function

Answer 8

a higher-order function that processes a data structure, typically a list, in some order to produce a new data structure containing exactly those elements of the original data structure that match a given condition.

Question 9

what is the reduce or fold function

Answer 9

a higher-order function which reduces a list of values to a single value by repeatedly applying a combining function to the list values.

-can be started from the left or right of the list

Question 10

what is the head and tail of a list

Answer 10

head: first element in a list
tail: all remaining elements

Question 11

how do you return the head of a list

Answer 11

head list_Name

Question 12

how do you return the tail of a list

Answer 12

tail list_Name

Question 13

how do you test for a empty list

Answer 13

null list_Name

Question 14

how do create an empty list

Answer 14

list_Name = []

Question 15

how do you return a list length

Answer 15

length list_Name

Question 16

how do you prepend an item to a list

Answer 16

newValue: list_Name

or

[newValue] ++list_Name

this doesnt change the list but instead cretaes a new one as the values are immutable

Question 17

how do you append an item to a list

Answer 17

list_Name ++ [newValue]

or

create a function that reverses the list, prepends the value and reverses the list again

let append y (x:xs) = reverse(y:reverse(x:xs))