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

Jason Wilkins jason.a.wilkins at gmail.com
Thu Apr 18 14:48:20 EDT 2013

Warning, this is a bit of a rant.

That paragraph from Wikipedia seems to be confused.  It gives the fourth
paradigm as "declarative" but then says "first order logic for logic
programming".  It seems somebody did an incomplete replacement of
"declarative" for "logic".  Wikipedia is often schizophrenic like that.

Personally, I think that object oriented and logical programming only
became official paradigms because there was a certain level of hype for
them in the 1980s and nobody has thought to strike them off the list after
the hype died down.

Object-oriented, as constituted today, is just a layer of abstraction over
imperative programming (or imperative style programming in functional
languages, because objects require side-effects).  What "object-oriented"
language actually in use now isn't just an imperative language with fancy
abstraction mechanisms?

The problem with having declarative languages as a paradigm (which logical
languages would be a part) is that it feels like it should be a
"miscellaneous" category.  Being declarative doesn't tell you much except
that some machine is going to turn your descriptions of something into some
kind of action.  In logical programming it is a set of predicates, but it
could just as easily be almost anything else.  In a way all languages are
"declarative", it is just that we have some standard interpretations of
what is declared that are very common (imperative and functional).

My wish is that the idea of there being four paradigms would be abandoned
the same we the idea of four food groups has been abandoned (which may
surprise some of you).  We have more than four different modes of thinking
when programming and some are much more important than others and some are
subsets of others.  We should teach students a more sophisticated view.

Ironically Wikipedia also shows us this complexity.  The
programming language paradigm side bar actually reveals the wealth
of different styles that are available.  There is simply no clean and
useful way to overlay the four paradigms over what we see there, so it
should be abandoned because it gives students a false idea.

On Wed, Apr 17, 2013 at 9:42 AM, Andreas Abel <andreas.abel at ifi.lmu.de>wrote:

> [ The Types Forum, http://lists.seas.upenn.edu/**
> mailman/listinfo/types-list<http://lists.seas.upenn.edu/mailman/listinfo/types-list>]
> On 17.04.2013 11:30, Uday S Reddy wrote:
>> 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."
> I removed the second sentence relating paradigms to computation models
> and put it on the talk page instead.  It does not make sense to connect
> imperative programming to Turing machines like functional programming to
> lambda calculus.  A better match would be random access machines, but the
> whole idea of a connection between a programming paradigm and a computation
> model is misleading.
>  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
> --
> Andreas Abel  <><      Du bist der geliebte Mensch.
> Theoretical Computer Science, University of Munich
> Oettingenstr. 67, D-80538 Munich, GERMANY
> andreas.abel at ifi.lmu.de
> http://www2.tcs.ifi.lmu.de/~**abel/ <http://www2.tcs.ifi.lmu.de/~abel/>

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