Transcript Presentation1

FORTRAN
1955
Procedural
SQL
1986
Database
ALGOL
1958
Procedural
Perl
1987
Tex extractoion
COBOL
1959
Procedural
HTML
1994
Hypertext
BASIC
1963
Procedural
LISP
1958
Functional
Pascal
1971
Procedural
Scheme
1975
Functional
C
1974
Procedural
Prolog
1972
Logic
Modula-2
1977
Procedural
Occam
1987
Parallel
Ada
1979
Parallel
Linda
1987
Parallel
Smalltalk
1971-80
Object Oriented
JavaScript
1996
Scripting
C++
1983
Object Oriented
VBScript
1996
Scripting
VB
1988
Object Oriented
Java
1995
Object Oriented
C#
2000
Object Oriented
Food for Thought
• Panini
• Curry
Paradigms: Imperative
• Focus on dynamic aspect of computation – operational semantics
• Specifies step-by step what must be done
Pure Forms
• Godel’s purely descriptive recursive function formalism
• Realized by Mc.Carthy’s Lisp
• Turing’s Imperative formalism
Paradigms: Functional
Paradigms: Logic
Paradigms: Object Oriented
Paradigms: Event Driven
Some Initial Thoughts, and Recap
• From the Church-Turing thesis all computers are equivalent to a Turing
Machine and therefore are equivalent to each other.
• Computer manufacturers admit this; they do not say “our machine has
some magic instruction which makes our computer more powerful than the
competition”. Their advertising goes like this: “Our machines are faster,
cheaper, easier to program and are more greener”
• From the Church-Turing thesis all programs can be constructed using
two registers and two instructions, so all programming languages are
equivalent in expressibility (power,…)
• Language developers admit this; they do not say “our language has
some magic feature which allows our language to do more than in any
other language”. Instead, their advertising goes like this. “Our language is
more user-friendly, our compilers are faster and they produce smaller
executable files, and are more greener”
Why are these two instructions so
fundamental?
decjmpreg reg,lab
inc reg
Programming Paradigms
What is a “Paradigm” ?
Important
Paradigms
• Imperative (procedural)
• Functional
• Logic
• Object Oriented
• Event Driven
Using conditional expressions to
define recursive functions
Thesis: All computable functions can be defined by the
recursive use of conditional expressions.
if p then a else b
n! = g(n,1)
where
g(n,s) = if n = 0 then s else g(n – 1, n x s)
Equivalence of imperative and
functional programming
Flow Diagrams: Turing Von
Neumann and McCarthy
Prolog Syntax Sheet
Facts and Rules
parent(abraham, isaac).
Fact. Lower case for names.
parent(isaac, esau).
Fact. Lower case for names.
grandfather(X,Y) :- parent(X,A),parent(A,Y).
Rule. If X is the grandfather of Y then X is the parent of A and A is the
parent of Y. For example, if george “X” is the parent of colin “A” and colin “A” is the
parent of tristan “Y” then george “X” is the grandparent of Tristan “Y”.
Queries
?- parent(abraham,X).
The capital X designates an “output” variable which will be all sons of
Abraham.
?- grandfather(abraham,X).
The capital X designates an “output” variable which will be all grandchildren
of Abraham.
What Programming Languages do we know?
FORTRAN
COBOL
C/C++
ADA
Java
C#
Scheme
Prolog
Occam
COBOL
SmallTalk
Java
Ada
C#
Assembler
ALGOL 60
Basic
FORTRAN
Haskell
F#
Lua
Python
Joy
Clean
Lisp
Oz
Pascal
Prolog
Scheme
FP
Erlang
OO
Imperative
Functional
Logic
Lang
Lang
Lang
Lang
Lang
Lang
Paradigm
Lang
Lang
Paradigm
Paradigm
Lang
Paradigm
Lang
Lang
Lang
Assembly
C
Imperative
Java
Functional
Matlab
Logic
ActionScript
Object Oriented
C++
Event Driven
Lisp
Prolog
Criteria for Comparison
Prolog
Scheme
asm
Java
C
Criteria
Procedural
int a,b,c
a = 1;
B = 46;
c = a + b;
ADD A TO B GIVING SUM
Recursion
Recursion
Talking on line 1 I
got a call on line 2
Talking on line 2 I
got a call on line 3
Talking on line 3 I
got a call on line 4
Talking on line 4 I
got a call on line 5
Talking on line 5 I
got a call on line 6
James I
Charles I
Catherine
Charles II
Elizabeth
James II
Sophia
George I
Why Babel?
Why Babel?
“ a language was designed to meet needs “
… so were cars…
Procedural (Imperative)
Fortran
10 IF(NUM .LT.0 GO TO 20
…
READ(*,*) NUM
GO TO 10
20 …
DIjkstra: “Go To Statement Considered Harmful”
Java, C#, C++, C
COBOL
ADD A TO B GIVING SUM
Sum = a + b;
HTML
SQL
New Paradigms
Functional = Scheme
Logic
= Prolog
A
(
A
)
+
A
var
A
(
A
)
+
A
var
Statement
var
=
expression
Expression
+
term
-
+
term
-
Term
var
num
(
expression
)
I’ve Lost my new mobile’s number
• I dumped my “brick” and bought an “Alcatel” (O2). Movie on Wednesday
• Jeez: I lost the paperwork and my new number. What to do?
• Get my girlfriend to call all numbers in the world, and I will wait for the call.
• Does this work (hehe) ?