Data Types

Question 1

Data types may be either:

Answer 1

Basic data types;
List data types;
Tuple data types;
Algebraic data types.

Question 2

What is a basic data type?

Answer 2

A small 30 bit integer i.e. 42 :: Int

A character i.e. ‘A’ :: Char

Question 3

What is a List data type?

Answer 3

Empty [] :: [Int]
An element prefixed to a list with :
42 : [] :: [Int]

Elements in a list must have the same type.

(a list may be written more compactly with commas)
(a list of characters can be written as a String).

Question 4

What is a Tuple data type?

Answer 4

A tuple data type is a number of elements in parentheses separated by commas
(1, ‘abcde’, 4) :: (Int, String, Int)
Elements may have different types but there are always a fixed number.

Question 5

What are algebraic types?

Answer 5

An algebraic type is an arbitrary combination of sums of products
i.e.
data Tree
      = Tip
       | Node Tree Int Tree

Question 6

A polymorphic algebraic type has type variables:

Answer 6

data Tree a
= Tip
| Node (Tree a) a (Tree a)