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Subject: Re: [TYPES] The type/object distinction and possible synthesis of OOP and imperative programming languages
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From: Robert Harper <rwh@cs.cmu.edu>
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Date: Thu, 18 Apr 2013 17:14:13 -0400
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To: Jason Wilkins <jason.a.wilkins@gmail.com>
Cc: types-list@lists.seas.upenn.edu, Python List <python-list@python.org>, Andreas Abel <andreas.abel@ifi.lmu.de>
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In short, there is no such thing as a "paradigm".  I agree fully.  This =
term is a holdover from the days when people spent time and space trying =
to build taxonomies based on ill-defined superficialities.  See Steve =
Gould's essay "What, If Anything, Is A Zebra?".  You'll enjoy learning =
that there is, in fact, no such thing as a zebra---there are, rather, =
three different striped horse-like mammals, two of which are genetically =
related, and one of which is not.  The propensity to be striped, like =
the propensity to have five things (fingers, segments, whatever) is a =
deeply embedded genetic artifact that expresses itself in various ways.

Bob Harper

On Apr 18, 2013, at 2:48 PM, Jason Wilkins wrote:

> [ The Types Forum, =
http://lists.seas.upenn.edu/mailman/listinfo/types-list ]
>=20
> Warning, this is a bit of a rant.
>=20
> 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.
>=20
> 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.
>=20
> 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?
>=20
> 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).
>=20
> 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.
>=20
> 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.
>=20
>=20
> On Wed, Apr 17, 2013 at 9:42 AM, Andreas Abel =
<andreas.abel@ifi.lmu.de>wrote:
>=20
>> [ The Types Forum, http://lists.seas.upenn.edu/**
>> =
mailman/listinfo/types-list<http://lists.seas.upenn.edu/mailman/listinfo/t=
ypes-list>]
>>=20
>> On 17.04.2013 11:30, Uday S Reddy wrote:
>>=20
>>> Mark Janssen writes:
>>>=20
>>> From:  en.wikipedia.org: Programming_paradigm:
>>>>=20
>>>> "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."
>>>>=20
>>>=20
>> 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.
>>=20
>>=20
>> 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?
>>>>=20
>>>=20
>>> These distinctions are not fully valid.
>>>=20
>>> - Functional programming, logic programming and imperative =
programming are
>>> three different *computational mechanisms*.
>>>=20
>>> - Object-orientation and abstract data types are two different ways =
of
>>> building higher-level *abstractions*.
>>>=20
>>> 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.
>>>=20
>>> Cheers,
>>> Uday Reddy
>>>=20
>>>=20
>>=20
>> --
>> Andreas Abel  <><      Du bist der geliebte Mensch.
>>=20
>> Theoretical Computer Science, University of Munich
>> Oettingenstr. 67, D-80538 Munich, GERMANY
>>=20
>> andreas.abel@ifi.lmu.de
>> http://www2.tcs.ifi.lmu.de/~**abel/ =
<http://www2.tcs.ifi.lmu.de/~abel/>
>>=20