CSC302 2011S, Class 01: An Introduction to the Course

Overview:
* What is a programming language?
* Why do we study programming languages?
* How should we study programming languages?

Admin:
* For Thursday (or, preferably, before), do the introductory survey.
* Reading for Wednesday (respond Tuesday evening): Tate, 2.1-2.2.
* Microsoft is giving Thursday's Thursday extra.  (Not in CS; Held in CDO or
  something.)

What is a programming language?
* An constructed language in which one produces programs 
  [unambiguously precise sets of instructions] that a computing device
  (mechanical, human, or whatever) can use to solve a task or tasks

Do we use programming languages to do more than write instructions?
* We sometimes use them to model data

Additional issues:
* The instructions often get "reduced" to something simpler
* And they end up being so simple that they are transparent
* We like them to communicate ideas

Here are some definintions I've collection.
  + Hoare (in part): A tool to aid the programmer.
  + Louden: A notational system for describing computation
    in machine-readable and human-readable form.
  + Matsumoto: [T]he means of programming but also
    enhancers for you mind that shape the way you think about programming.
  + Reade: One, rather narrow, view is that a program is a
    sequence of instructions for a machine. We hope to show that there is
    much to be gained from taking the much broader view that programs
    are descriptions of values, properties, methods, problems, and
    solutions. The role of the machine is to speed up the manipulation
    of these descriptions to provide solutions to particular problems.
    A programming language is a convention for writing descriptions
    which can be evaluated.
  + Rebelsky: A notation for expressing algorithms so that they
    may be understood by humans and processed by machines.
  + Stansifer:  The purpose of language is communication.  Human
    beings use natural languages to communicate among themselves.  
    Programming languages are used to communicate with literal-minded
    machines.  
  + Webopedia: 
    A vocabulary and set of grammatical rules for instructing a computer
    to perform specific tasks. The term programming language usually
    refers to high-level languages, such as BASIC, C, C++, COBOL, FORTRAN,
    Ada, and Pascal. Each language has a unique set of keywords (words
    that it understands) and a special syntax for organizing program
    instructions.
  + Wikipedia: A programming language is an artificial language 
    designed to express computations that can be performed by a machine, 
    particularly a computer. 

Do these add anything to our definition?  
* A little clarification, but at the cost of concision and conciseness

Why do we study them?  (We do we devote a class to it?)
* Practical: Different languages are better or worse suited to different
  problems.  By learning different languages, we can choose the ones
  better suited to particular problems.
  * OOP is better suited to Web programming than imperative
    * Because Web systems are normally large, and the key aspects of
      OOP make it easier to manage large systems
      * Polymorphism, Inheritance, Encapsulation
      * The language enforces barriers and encourages reuse
  * Functional languages are better at data-oriented problems
* Practical: Jobs: Meet the HR requirement of "Knows Ruby/Java/Python/C/C--/..."
* General: It's cool and interesting
* Practical: The more languages you know, the easier it is to learn a 
  new one
* Although all the languages can eventually do the same thing, learning
  new ways to do it can change the way we think about problem solving
  "enhancers for you mind"
* Practical: These days, you need to know lots of languages

Inner product: Given two vectors (or lists), A and B, compute
  sum of A[i]*B[i]

  for (i = 0; i < n; i++)
    sum += A[i]*B[i]

  (fold + (map * A B))

Why use one?
* for loop is more straightforward
* Functional one is "more interesting"
* Functional one is closer to the specification
* Functional one is easier to parallelize

How does one teach this class?
* The language of the week approach
* The "interpreter of the week" approach
* The "lots of key issues" approach
* The "primary literature" approach

Structure of the class
* Weeks 1-8: Language of the Week
* Weeks 9-11: Primary Literature and Key Issues
* Weeks 12-13: Key Issues and New Languages Through Student Presentations
* Week 14: Wrapup