Principle of programming language -M.E-CSE

Principle of programming language -M.E-CSE

• 1.
  CS 331, Principlesof Programming Languages Introduction
• 2.
  Objectives • To introduceseveral different paradigms of programming – But isn’t one language pretty much like another? No! • To gain experience with these paradigms by using example programming languages • To understand concepts of syntax, translation, abstraction, and implementation
• 3.
  Paradigms of Programming? •There are several ways to think about computation: – a set of instructions to be executed – a set of expressions to be evaluated – a set of rules to be applied – a set of objects to be arranged – a set of messages to be sent and received
• 4.
  Some Programming Paradigms •Procedural – examples: C, Pascal, Basic, Fortran • Functional – examples: Lisp, ML • Object-oriented – examples: C++, Java, Smalltalk • Rule-based (or Logic) – example: Prolog
• 5.
  Why so many? •Most important: the choice of paradigm (and therefore language) depends on how humans best think about the problem • Other considerations: – efficiency – compatibility with existing code – availability of translators
• 6.
  Models of Computation •RAM machine – procedural • directed acyclic graphs – Smalltalk model of O-O • partial recursive functions – Lisp and ML • Markov algorithms – Prolog is loosely based on these
• 7.
  Lots of Languages •There are many programming languages out there • Lots of other PL-like objects – document languages, e.g. LaTeX, Postscript – command languages, e.g. bash, MATLAB – markup languages, e.g. HTML and XML – specification languages, e.g. UML
• 8.
  Issues for allLanguages • Can it be understood by people and processed by machines? – although translation may be required • Sufficient expressive power? – can we say what needs to be said, at an appropriate level of abstraction?
• 9.
  Translation • Compilation – Translateinto instructions suitable for some other (lower level) machine – During execution, that machine maintains program state information • Interpretation – May involve some translation – Interpreter maintains program state
• 10.
  Trade-offs • Compilation – lowerlevel machine may be faster, so programs run faster – compilation can be expensive – examples: C (and Java?) • Interpretation – more ability to perform diagnostics (or changes) at run-time – examples: Basic, UNIX shells, Lisp