Oberon: procedure interfaces, parameter modes, and strict typing (1992)

Comments

• GregorGB

  January 13 edited January 15

  To address the questions, I would like to put another code snippet up for discussion:

  • Structure and Interpretation of Computer Programs (SICP), Ch. 1.1

  tl;dr My impression is that Oberon and Scheme (or SICP) are examples of languages that have a certain idea of computer science and programming in mind: mathematical, principle-driven, simple, which they attempt to incorporate into teaching. The goal of teaching is understood as something that benefits from these principles. In contrast, Vakil (2018) and Schulte and Budde (2018) have each argued that the goals of computer science education should be far less technical. Both see CS as a tool for self-empowerment that creates a just society and responsible citizens in a digital society. This naturally raises the question: if Oberon and Scheme are not the right tools for this, what is?
• michael.falk

  January 13

  Thanks Gregor for citing the great SICP. That book can't be cited enough!

  Sussman and Abelson set out the idea that computer science is about "procedural knowledge," as opposed to mathematics, which is "declarative." By this they meant that computer science is the study of procedures to do things. It follows (more or less) that the ideal programming language is a language for specifying procedures, or if you prefer the ALGOL way of putting it, for describing algorithms.

  Oberon is obviously an ALGOL-type language, which is hardly surprising given Wirth's involvement in its design and development.

  It is quite common to trash the idea of studying algorithms today. I can recall Ben Schmitt writing a piece in I think The Atlantic about falling enrolments in HASS across the US. Lamenting the corresponding rise in Computers Science enrolments, he posed a question like "Do we really need all these undergraduates to know the quicksort algorithm?"

  I don't like that rhetorical question at all. The enthymeme is clearly "it would be much better for students to acquire historical knowledge." But the rhetorical question can easily be turned on the Humanities: "Do we really need all these undergraduates to know that Carthage was sacked in 146 BCE?" Quite obviously the date of the sack of Carthage is not a valuable fact on its own. Nor is the quicksort algorithm. The sack of Carthage is interesting when it forms part of a broader history curriculum where students acquire knowledge of source analysis, politics, class, rhetoric etc. Likewise quicksort is interesting when it forms part of a broader curriculum about how to structure computations.

  I think Sussman and Abelson were having a mid-life crisis when they let MIT give up on Scheme. Some of their colleagues in Singapore updated the curriculum in I think a much nicer way: by re-writing SICP to use JavaScript instead of Scheme. In one stroke, they preserved the philosophical underpinnings of SICP, while also addressing silly anxieties about "industry relevance."

  The Oberon-level is a good level on which to think of computations. CCS works well at the Oberon-level: inspecting individual lines, functions, subroutines, control blocks. If I may quote SICP again, the authors themselves indicate how their level of analysis might form the basis for a more humanistic critique of programming. In their discussion of functional vs. object-oriented styles, they write:

  In this chapter we will investigate two prominent organizational strategies arising from two rather different “world views” of the structure of systems. The first organizational strategy concentrates on objects, viewing a large system as a collection of distinct objects whose behaviors may change over time. An alternative organizational strategy concentrates on the streams of information that flow in the system, much as an electrical engineer views a signal-processing system.

  They are essentially saying that functional programming implies a Whiteheadian process metaphysics, while object-oriented programming implies a Kantian metaphysics of discrete objects. I have found this passage inspiring, as a hinge on which a more technical view of code can pivot into a metaphysical and/or ideological view.
• Waliya

  January 17

  You mean, worldview could be buried inside coding: "more technical view of code can pivot into a metaphysical and/or ideological view". Wow! How could you justify this in this snippet "
  CONST x1 = 1; x2 = 2; x3 = 3; x4 = 4; x = 3.14159;
  VAR a, b, c, aR, bR, aI, bI: REAL; i: INTEGER;
  xR, yR, xI, yI: LONGREAL;
  PROCEDURE Root(a, b, c: REAL; VAR x1, x2, y1, y2: REAL);
  PROCEDURE Sin(x: REAL): REAL;
  PROCEDURE Min(x, y: INTEGER): INTEGER;"