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Programming Languages. CS 430/CS 530 Fall 2004 Professor Adams. Programming Languages. facilitate the expression and communication of ideas between people have a narrower expressive domain than natural languages because they only communicate algorithmic ideas
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Programming Languages CS 430/CS 530 Fall 2004 Professor Adams
Programming Languages • facilitate the expression and communication of ideas between people • have a narrower expressive domain than natural languages because they only communicate algorithmic ideas • enable communication of algorithms between people and computers
Required definition of an Algorithm • An algorithm is an unambiguous, step-by-step procedure for solving a problem in a finite amount of time using a finite amount of space
Categories of Language Design Principles • Syntax • context-free grammar • Type systems and semantics • values that programs can manipulate • meaning of programs • Memory management • Exception handling
Memory Management • static memory • dynamic memory • stack • heap • lifetime of objects • techniques for garbage collection & storage reclamation
Exceptions • unexpected input • unexpected divide by zero • unexpected attempt to create a new block of space on the heap
Programming Paradigms • Imperative • Object-oriented • Functional • Logic (declarative) programming • Event-driven programming • Concurrent programming
Imperative Programming • Explicit series of steps • calculates, retrieves input, produces output • Procedural abstraction • assignments, loops, sequences, conditionals • Major imperative languages • Fortran (1954, IBM, John Backus), Cobol (Codasyl Committee), C (designed for and implemented on the UNIX operating system on the DEC PDP-11 by Dennis Ritchie) , C++, Ada
Object-Oriented Programming • Program is a collection of objects which pass messages to one another to transform their states • Object modeling, classification, inheritance are fundamental building blocks • Major OO languages • Smalltalk (Xerox PARC - Adele Goldberg & Alan Kay 1970’s), Java, C++, Eiffel
Functional Programming • Program is a collection of mathematical functions • input (domain) • result (range) • Functions interact & combine using • functional composition, conditionals, recursion • Major functional languages • Lisp (John McCarthy – M.I.T. – late 50’s), Scheme (block structure, lexical scoping, etc.), Haskell, ML
Logic (declarative) Programming • Program is a series of statements about what should happen rather than how it should be done • Expresses non-determinism • Major logic programming language • Prolog(Alain Colmerauer – Universite d’Aix Marseilles – 1972)
Event-driven Programming • Program is a continuous loop that responds to unpredictably ordered events • Events originate from • user actions (mouse clicks or keystrokes) • sensors on a robot • Major event-driven languages include • Visual Basic, Java
Concurrent Programming • Program is a collection of cooperating processes • Concurrent Programming Languages • SR, Linda, High Performance Fortran