The document provides information on three programming languages: COBOL, LISP, and Python. COBOL was released in 1959 and was used for 80% of business transactions due to industry collaboration and Cold War pressures. LISP was the second high-level language created in 1958 and introduced innovations like garbage collection and recursion using linked lists. Python was developed in the 1990s and prioritizes readability through design choices like whitespace and a simple grammar.

1. COBOL Background
 Released in 1959
 Grace Hopper
 Industry, universities, and government collaboration
 Cold War pressures
 80% of business transactions
 65% of all code is in COBOL

2. COBOL – Why?
 Software Lifecycle
 Cheaper to maintain
 Y2K
 Self-documenting code
 Verbose
 “IF a < b AND > c …”
 Divisions

3. COBOL – Why?
 Divisions
 Identification Division
 Environment Division
 Data Division
 Procedure Division

4. COBOL – Data Division
 Data Division
 Pictures
 9 = digit
 X = any character
 A = alphabetic character
 V = decimal point position
 S = sign
 Repeats
 PIC 9 (4) = 9999

6. COBOL – Groups and Elementary data

8. COBOL
 Reliability
 Stood test of time
 Has “ALTER X TO PROCEED TO Y” (a negative)
 Uses GOTO statements (a negative)
 Today
 Cross platform: OpenCOBOL C translation
 IDEs (Net Express)

9. COBOL - Summary
 Readability
 Writability
 Reliability
 Portability

10. LISP
 LISt Processing
 List-based language
 2nd High-level language
 1958 – John McCarthy for MIT

12. LISP - Syntax
 Function call: “(fun arg1 arg2)”
 (+ 1 2 3)
 Lists
 (list ‘3 ‘7 ‘apples)
 (3 7 apples)
 (list ‘13 list(‘3 ‘5))
 (13 (3 5))

13. LISP – Innovations
 Garbage Collection
 If else statements
 Recursion

14. LISP – Linked Lists
 Car (first)
 Cdr (rest)

16. LISP - Examples
 If then else
 (if nil
(list ‘2 ‘3)
(list ‘5 ‘6))
 One line variant:
 (if nil (list ‘2 ‘3) (list ‘5 ‘6))

17. LISP - Examples
 Factorial
 (defun factorial (n)
(if (<= n 1)
1
(* n (factorial (- n 1)))))
 One line variant:
 (defun factorial (n) (if (<= n 1) 1 (* n (factorial (- n 1)))))

18. LISP - Examples
 Recursive List Size
 (defun recursiveSize (L)
(if (null L)
0
(1+ (recursiveSize(rest L)))))

19. LISP - Examples
 Recursive List Sum with “LET”
 (defun sum (L)
(if (null L)
0
(let
((S1 (first L))
(S2 (sum (rest L))))
+ S1 S2)))

20. LISP- Summary and Comparison
 Readability
 Writability
 Reliability

21. Python
 Developed early 1990’s
 Guido van Rossum
 ABC language
 Python 2.0
 2000
 Community-supported -> reliability
 Modular; community expandable
 Python 3.0
 2008

22. Python – Readability is Key
 Design goal
 One way to do things
 Clarity over clever code
 Whitespace over braces
 “pass” for No-Op

23. Python
 Writability
 Similar to other OO languages
 Verification support
 Interpreted, assert, no statements in conditions
 Clean style
 Few keywords
 Simple grammar -> few ways to do something

24. Python
 Comparisons
 == tests values, not references
 A < b <= C works properly
 Ternary operator readable
 “a if b else c”

25. Python
 System Requirements
 Cross platform
 Python Interpreter
 Simplicity
 Small core language
 Large libaraies

26. Python - Examples
 a = 15
if(a < 10):
print(“input less than 10”)
elif(10 < a < 20):
print(“input between 10 and 20”)
else:
print(“input greater than 20”)

27. Python - Examples
 Function definition
def greatest(a, b, c):
largest = a if a > b else b
largest = largest if largest > c else c
print(largest)
 Function call
greatest(7, 3, 14)
14

28. Python - Examples
 Determine if prime
def isPrime(num):
prime = True
for i in range(2, (num / 2) + 1):
if num % i == 0:
prime = False
return prime

29. def tenPrimes():
list = []
count = 0
current = 2
#store the first 10 primes in a list
while count < 10:
if isPrime(current):
count += 1
list.append(current)
current = current + 1
#print the list
for element in list:
print(element)

30. Python - Summary and Comparison
 Readability
 Writability
 Reliability