On May 29, 5:32 am, Stef Mientki <[EMAIL PROTECTED]> wrote:
> Avowkind wrote:
> > On May 27, 6:34 am, [EMAIL PROTECTED] wrote:
>
> >> (might not be the right forum for this but...)
>
> >> what is the definition of a highlevel-language?
>
> >> well there isnt one specifically and wikipedia and the like gives just
> >> a very general description obv you can say it abstracts away lowlever
> >> operations.
>
> >> yes but how?
>
> >> a function like map takes a function and applies it to a list for
> >> example.
> >> this abstracts away a common procedure like iterate through a list and
> >> for every position do a computation.
> >> so it is a higherorderfunction. is this how higher-level-languages are
> >> built?
>
> >> so are they fundamentally differently built or is it just a lot of
> >> lowlevel operations built on top of each other?
>
> >> haskell is considered a very highlevellanguage but can you do
> >> systemsprogramming with it(yes maybe it is very unpractical i dont
> >> know but can you)?
>
> >> is lambda calculus a more abstract and efficient way of modeling a
> >> computer? meaning you start at a higher level of abstraction and can
> >> work up to even higher even faster?
>
> >> how did lispmachines work? was the basic system programmed in LISP?
>
> > A lot of the previous comments have been about levels of abstraction
> > of the programming langauge - which may be the answer you want.
> > Another way of looking at it is that we want to be able to move from
> > the language of the solution domain - e.g. computers, bits and bytes
> > to the language of the problem domain.
>
> > When we think about 'level' we don't just want to look at how basic
> > statements work. we also need to think about whether the language is
> > capable of simply and clearly expressing the problem.
>
> > If your problem domain is mathematics then mathcad and its ilk are
> > near perfect high level programming languages as the programs look
> > just like the problems.
>
> Andrew, that's very good description, and I totally agree !> if your problem
> domain is controlling a water works then you may tend
> > to write your problem like this:
>
> > if the water level is over 10 metres then start pump
> > if the water level is below 5 metres then stop pump
>
> I would go one step beyond that, and state the problem as:
> "keep the reservoir full, but not too full"> which in python might turn out
> to be
>
> > if water_level > 10:
> > pump.start()
> > if water_level < 5:
> > pump.stop()
>
> > which is fairly close.
>
> And now the solution is less close ;-)
> And it becomes even less close,
> if we extend your solution somewhat more to a real world implementation,
> something like this:
>
> control = True
> while control :
> if water_level > 10:
> pump.start()
> if water_level < 5:
> pump.stop()
>
> And if you would propose this solution to a control system engineer,
> he/she would say: "this solution works very bad" or even "this solution
> won't work"
> A solution that would work, should incorporate at least a hysteresis and
> could look like this:
>
> control = True
> State = False
> while control :
> if State and ( water_level > 10 ) :
> pump.start()
> State = not ( State )
> elif not ( State ) and ( water_level < 5 ) :
> pump.stop()
> State = not ( State )
>
> and now what's the resemblance to the orginal problem :
>"keep the reservoir full, but not too full"
> ;-)
>
> So an adequate high level language,
> should do exactly like a control engineer would do (btw I'm not a
> control engineer):
> 1- asking what do you mean by "full"
> 2- not asking what's the other level,
> but asking what's the intended use: how often and how many water is
> added or used,
> what are the costs of the pump, etc etc
> after which
>the control engineer
>or
> the high level language
> can calculate the optimal hysteresis.> of course with the addition of some
> brackets C++ could be this clear
> > too. The key though is the abstraction given by the pump class and
> > implicitly by object oriented design.
>
> > In this pattern Form designers, visual web page layout tools and their
> > ilk are very high level - but only if your problem is that you need to
> > design a lot of business forms or web pages. Some
