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

Uday S Reddy u.s.reddy at cs.bham.ac.uk
Wed Apr 17 05:30:36 EDT 2013

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.

Uday Reddy

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