On 20 Jan 2015, at 23:58, 'Chris de Morsella' via Everything List wrote:
Then it is a good thing that computer science did not listen to you
Kim, regarding the concept of "abstraction" and "abstract
classes" {e.g. templates for concrete entities fully implementing
the abstracted methods and properties} being -- in your opinion --
useless.
Abstraction is one of the guiding principles of good software
design; without abstraction and the ability to design abstract
partially implemented classes, building good extensible software
would become much harder to do.
In an informatic sense an entity is abstract when it cannot be
instantiated (until the abstract bits are given a concrete
implementation by a derived concrete class.
The ultimate abstraction, in computer science is the interface,
which defines a pure contract and is without implementation.
Interfaces can never e instantiated into real objects; only the
concrete implementation of the interface can ever exist in reality.
However, the interface does provide the guiding contract; it is the
template which the implementing concrete instance must implement or
fulfill. Interfaces and abstract base classes are both exceedingly
important and useful in modern software design.
Layers of abstraction are of central importance to the architecture
and building of non trivial software. If you value software and all
the products and services software makes possible then you too value
abstraction and the ability to think and interact in terms of
abstractions.... whether or not you are aware of them.
I agree, abstraction is important in mathematics, logic, and computer
science. Church's lambda calculus is a theory of abstraction, with
"lambda" being a formal rule of abstraction: it transforms a parameter
into a variable, for example:
F(x, y, z, t, r, s) =====> lambda x (lambda t (lambda s (F x, y, t, r,
s); which just means that the expression F, with parameter x, y, z,
t, r, s becomes the function with three variable (x, t, s) and two
parameters y, r.
Abstraction is very powerful. With application it is already Turing
universal. You can indeed easily simulate the combinator K and S:
K = lambda x (lambda y (x))
S = lambda (x (lambda y (lambda z ((x z) (y z)) ))
and K and S are Turing universal (for those who remembers the intro I
made to the combinators).
Bruno
-Chris
From: Kim Jones <kimjo...@ozemail.com.au>
To: "everything-list@googlegroups.com" <everything-list@googlegroups.com
>
Sent: Tuesday, January 20, 2015 1:32 PM
Subject: Re: Isn't this group supposed to be about trying to figure
out how the universe works and not so much about religion and insults?
On 21 Jan 2015, at 4:56 am, John Clark <johnkcl...@gmail.com> wrote:
On Tue, Jan 20, 2015 at 4:20 AM, Kim Jones
<kimjo...@ozemail.com.au> wrote:
> stop using that ridiculous and meaningless art term "abstract".
[...] Nothing is "abstract".
So you're saying that the word "abstract" should be removed from
the English language because it will never be needed?!
John K Clark
It's not a word that should be used, no. It implies that something
is taking a quick holiday in the Platonic realm, merely for the
benefit of the researcher who will fairly soon remove those
parentheses and pluck said object "out of" abstraction land and back
into "the real world". It's another example of how embedded in our
culture is the idea that the non-physical exists, yet this word
seems to sanctify such an anomaly for a physicalist, momentarily
allowing him to use it with impunity. Platonists have no need for
such a term because everything is abstract already. The problem of
needing such a word to make it possible for a physicalist to talk
about the immaterial without being kneecapped by other physicalists
occurs only in a "material universe."
I believe there exist words that are dangerously misleading and this
is one of them. I equally believe there are great many more words
which should exist but which don't, except as a "need".
There are only needs. Needs are proof of the existence of persons.
These needs get expressed as beliefs which are frozen as words.
Needs, however, evolve along with the environment they relate to and
some needs can even or should even evaporate as our knowledge
increases. Language continually lugs around ancient needs frozen
solid. This is a very great problem in communication.
K
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