[TYPES] The type/object distinction and possible synthesis of OOP and imperative programming languages

Rishiyur Nikhil nikhil at acm.org
Wed Apr 17 10:04:02 EDT 2013

>    If you have trouble getting hold of "The Essence of Algol", ...

There seems to be a downloadable copy at:


It's in PostScript, which is easily convertible to PDF if you wish.


On Wed, Apr 17, 2013 at 5:30 AM, Uday S Reddy <u.s.reddy at cs.bham.ac.uk>wrote:

> [ The Types Forum, http://lists.seas.upenn.edu/mailman/listinfo/types-list]
> Mark Janssen writes:
> > From:  en.wikipedia.org: Programming_paradigm:
> >
> > "A programming paradigm is a fundamental style of computer
> > programming. There are four main paradigms: object-oriented,
> > imperative, functional and declarative. Their foundations are distinct
> > models of computation: Turing machine for object-oriented and
> > imperative programming, lambda calculus for functional programming,
> > and first order logic for logic programming."
> >
> > While I understand the interest in purely theoretical models, I wonder
> > two things:  1)  Are these distinct models of computation valid?  And,
> > 2) If so, shouldn't a theory of types announce what model of
> > computation they are working from?
> These distinctions are not fully valid.
> - Functional programming, logic programming and imperative programming are
> three different *computational mechanisms*.
> - Object-orientation and abstract data types are two different ways of
> building higher-level *abstractions*.
> The authors of this paragraph did not understand that computational
> mechanisms and higher-level abstractions are separate, orthogonal
> dimensions
> in programming language design.  All six combinations, obtained by picking
> a
> computational mechanism from the first bullet and an abstraction mechanism
> from the second bullet, are possible.  It is a mistake to put
> object-orientation in the first bullet.  Their idea of "paradigm" is vague
> and ill-defined.
> Cheers,
> Uday Reddy

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