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List: (a) arr [1, 2, 34]

(e) x= [2, 5, 6.5, [5,6], 8.2]

Tuple: (b) arr (1, 2, 34)

(d) day = (‘sun’ , ‘mon’, ‘tue’ , ‘wed’)

Class: (c) student [mo, name, mark]

(f) employee [eno, ename, esal, eaddress]

You can now represent a rational number as a pair of two integers in pseudo code: a numerator and a denominator.

rational (n, d):

return [n, d]

numer (x):

return x [0]

denom (x):

return x [1]

Representation of Tuple as a Pair

nums : = (1, 2)

nums [0]

1

nums [1]

2

nums [1] indicate that we are accessing 2 element.

Pair is a compound structure

Bundling two values together into one can be considered as Pair

The following pseudo code will compute the distance between two city objects:

distance(city 1, city2):

1t1, 1g1: = getlat (city1), getlon (city1)

1t2, 1g2: = getlat (city2), getlon (city2)

return ((1t1 – 1t2) ** 2 + (1g1 – 1g2) ** 2)^1/2

A sequence of immutable objects is called Tuple

A class as bundled data and the functions that work on that data.

nums [1] represent that you are accessing 1 element.

(d) Abstract datatype

(c) Concrete data type

Lists is constructed by placing expressions within square brackets

Constructors are functions that build the abstract data type. Selectors are functions that retrieve information from the data type.

To create a city object, you’d use a function like

city = makecity (name, lat, Ion)

To extract the information of a city object, you would 

use functions like

getname (city)

A tuple is a comma-separated sequence of values surrounded with parentheses. Tuple is similar to a list. The difference between the two is that you cannot change the elements of a tuple once it is assigned whereas in a list, elements can be changed.

Example colour = (‘red’ , ‘blue’ , ‘Green’)

We are using here a powerful strategy for designing programs: 

‘wishful thinking’. Wishful Thinking is the formation of beliefs and making decisions according to what might be pleasing to imagine instead of by . appealing to reality.

(a) City = makecity(name, lat, lon)

There are 2 ways of representing pair data

Answer (c) Classes

many objects can be created from a class

Classes are the representation for ADT.

(d) Abstraction

(c) Both a and b

The two parts of a program are, the part that operates on abstract data and the part that defines a concrete representation.

(a) Modularity

List is constructed by placing expressions within square brackets separated by commas.

Example for 

List is [10, 20].

The elements of a list can be accessed in two ways. The first way is via our familiar method of multiple assignment, which unpacks a list into its elements and binds each element to a different name.

1st: = [10, 20]

x, y: = 1st

In the above example x will become 10 and y will become 20.

A second method for accessing the elements in a list is by the element selection operator, also expressed using square brackets. Unlike a list literal, a square – brackets expression directly following another expression does not evaluate to a list value, but instead selects an element from the value of the preceding expression.

1st [0]

10

1st [1]

20

(a) Constructors

List is constructed by placing expressions within square brackets separated by commas.

Example for List is [10, 20].

In list 1st [(0, 10), (1, 20)] – 0 and 1 represents Index

(b) Selectors

(a) N1 = number ( ) – constructors

(b) Accetnum (n1) – selectors

(c) Displaynum (n1) – selectors

(d) eval (a/b) – selectors

(e) x, y = makeslope(m), makeslope (n) – constructors

(f) display O – selectors

(d) Both a and b

(c) Abstract data types

Concrete data type:

1. A concrete data type is a data type whose representation is known.

2. Concrete data types or structures (CDT’s) are direct implementations of a relatively simple concept.

Abstract data type:

1. Abstract data type the representation of a data type is unknown.

2. Abstract Data Types (ADT’s) offer a high level view (and use) of a concept independent of its implementation.

Abstract Data type (ADT) is a type (or class) for objects whose behavior is defined by a set of value and a set of operations. The definition of ADT only mentions what operations are to be performed but not how these operations will be implemented.

2  types of functions are needed to facilitate abstraction

Two ways of representing the pair data type. The first way is using List construct and the second way to implement pairs is with the tuple construct.