Programming Language Concepts (CS 360) Lecture 1: Overview, Grammars, and Little Languages

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Programming Language Concepts(CS 360)Lecture
1 Overview, Grammars, and Little Languages

• Jeremy R. Johnson
• (Guest Lecturer)

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Basic Info

• Instructor
• Sam Moelius
• Email smoelius_at_cs.drexel.edu
• Office Hours TBD
• Text
• Concepts of Programming Languages, 5th Ed.
• Robert W. Sebesta
• Addison Wesley
• Web Page
• TBD
• Mailing List
• TBD

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Course Description

• Introduces the design and implementation of
  modern programming languages formal theory
  underlying language implementation concerns in
  naming, binding, storage allocation and typing
  semantics of expressions and operators, control
  flow, and subprograms procedural and data
  abstraction functional, logic, and
  object-oriented languages. Students will
  construct an interpreter for a non-trivial
  language.

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Course Prerequisites

• CS 171 (Prog. I), 172 (Prog. II), and 260 (Data
  structures)
• Comfortable with an object-oriented language
  (ideally should have seen at least two languages)
• Ideal
• CS 281 (Systems Architecture I) understanding
  of the underlying of basic computer architecture
  (assembly language, machine organization)
• CS 270 (Foundations of Computer Science) should
  be comfortable with the mathematical tools used
  to describe and analyze programming languages
  (logic, recursion material on finite state
  machines and grammars useful but will be covered
  in this class)

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Course Themes

• Tools to evaluate design of languages
• Tools for describing and analyzing languages
• syntax
• semantics
• Tools to design new languages
• Programming Paradigms
• Implementation of programming languages

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Course Objectives

1. Understand how to compare and evaluate different
   programming languages and know what factors need
   to be taken into account.
2. Be comfortable with the major programming
   paradigms and be able to use at least one
   language from each paradigm.
3. Understand some of the issues involved in
   implementation of programming languages this
   should help them program more efficiently.
4. Be familiar with elementary concepts of formal
   language theory such as context-free grammar.
5. Be able to formally specify the syntax of
   programming languages.
6. Be familiar with the essentials of lexical
   analysis and elementary parsing procedures.
7. Understand dynamic and static scope, dynamic and
   static binding and the issues they give rise to.
8. Understand the advantages and disadvantages of
   strong/weak type checking.
9. Understand the different methods of parameter
   passing and how they might be implemented and
   understand some of the issues involved in calling
   subroutines.
10. Understand generic programming.

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Tentative Topics

• Week 1 Overview and introductions to grammars
  (ch. 1 3)
• Week 2 Functional Languages (ch. 15)
• Week 3 Logic Programming Languages (ch. 16)
• Week 4 Syntax, Types, Scanning, and Parsing (ch.
  3-5)
• Week 5 Midterm (more on types and type checking)
• Week 6 Data types and Memory allocation (ch. 6)
• Week 7 Program semantics and interpreters (ch.
  3)
• Week 8 Control Structures. Iteration versus
  Recursion and their implementation. Templates in
  C and generic programming and its advantages
  and pitfalls (ch. 7-9).
• Week 9 Subroutines and Parameter Passing
  Methods, Implementing subroutines (ch. 9-10).
• Week 10 Abstract data types and object-oriented
  programming (ch. 11-12)

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Course Benefits

• Easier to express ideas
• Improved background for selecting appropriate
  languages
• Easier to learn new languages
• Understand the significance and impact of
  language choices and constructs
• Design new languages (little languages, interface
  specifications, protocols)
• Overall advancement of computing

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Grading Policy

• Assignments (Programming Description
  Evaluation)
• 5 _at_ 10 each
• Midterm Exam
• 25
• Final Exam
• 25
• Grades will be determined using a curve with the
  weighted average equal to a B provided the
  average shows understanding of the material.
• All work must be completed independently unless
  explicitly stated other wise. Not following this
  rule is subject to receiving a 0 for the first
  offense and subsequent offenses may lead to a
  lower or failing grade.

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Outline (Ch. 1)

• Programming Domains
• Programming Paradigms
• Language Evaluation Criteria
• Readability
• Writability
• Reliability
• Cost
• Influences on language design
• Computer architecture
• Programming methodologies
• Language categories
• Imperative
• Functional
• Logic
• Object-oriented
• Implementation methods
• Interpreter
• Compiler
• Hybrid

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Programming Domains

• Scientific Computing
• FORTRAN
• C, C
• Matlab, Maple, Mathematica
• Business Applications
• COBOL
• Spreadsheet, DB, SAP
• Systems Programming
• assembly
• PL/S, BLISS, C
• Scripting Languages
• sh, ksh, bash
• awk, perl, python
• Artificial Intelligence
• lisp, prolog
• Special-purpose languages

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Programming Paradigms

• Imperative (procedural)
• Algol, C, FORTRAN, Pascal
• Data Abstraction
• Modula-2
• Object Oriented
• Simula 67, Smalltalk, C, java, Ada 95, Eiffel
• Functional
• Lisp, Scheme, ML
• Logic (declarative rule based)
• prolog
• Parallel
• Hardware Description Languages
• Markup
• Special-purpose

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Evaluation Criteria

• Readability
• Simplicity
• Orthogonality
• Control statements
• Appropriate data types
• Syntax considerations
• Writability
• Simplicity and orthogonality
• Support for abstraction
• Expressivity
• Reliability
• type checking
• exception handling
• Aliasing
• Cost
• readability and the learning curve
• writability and naturalness of the language for
  the application
• compilation and execution time

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Compilation
Source Program
Results
Lexical Analyzer
Computer
User Inputs
Lexical Units
Syntax Analyzer
Machine Language
Code Generator
Parse Tree
Intermediate Code Generation
Symbol Table
Optimizer
Intermediate Code
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von Neumann Architecture

• Fetch-Execute Cycle
• Initialize PC, Registers
• Repeat
• Fetch Instruction
• Increment PC
• Decode Instruction
• Execute Instruction

Memory
Control
ALU
I/O
CPU
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Interpretation
Source Program
Interpreter
User Inputs
Results