Re: text equation

Jim wrote:
>Years ago (10 or so) I would of said, yes, Perl was a high level
>language, but I think with the advent of improved technology
>that a shift has occurred, and it is more of a mid level language.
>
>I do agree, however, that my concept of a "high level language"
>is probably not what the rest of the computer community thinks
>of, so I should of probably said it was not a higher level language?
>
>Or perhaps it is just that I do not understand Perl enough to
>know of it's capabilities.
>
>To me, the higher level the language the more machine code is
>produced for each line of source.  Optimized machine code too.
>
>C is not considered a high level language (or it used to not be)
>because it was very close to the hardware.  C has gotten a bit
>higher level, but not as much as some.
>
>Assembly is extremely low level because there is almost a 1:1
>correlation between source code and machine code.
>
>Perl and Rexx, however, are somewhat hard for me to place,
>the same as Basic used to be, because they are interpreted.
>I really don't know where to place interpreted languages in the
>scheme of things.  Anything that is interpreted and not compiled
>to executable format, in my opinion, is a little bit lower level
>than if the same source was compiled.


Oh dear oh dear oh dear!  Where to begin!

You said "To me, the higher level the language, the more
machine code is produced for each line of source."  This
is one source of problems for you since you later admit
that you don't know where to fit interpreted languages,
like Perl and Rexx.  Add Java to that and you'll really
see how inadequate your definition is!

Perhaps a more useful definition would be "the higher
level the language, the more stuff is done for you by the
language."  No, that still doesn't seem quite right to me,
but perhaps that fits more what you had in mind.

                     - - - - -

Personally, I like to think of programming languages as
consisting of various levels of abstraction above the
hardware.  In the past, a lot of people talked about
generations of programming languages - I like to
classify languages by decade.  In each decade during the
recent history of computing, languages featured additional
levels of abstraction:

1940's - bare hardware
1950's - operations were abstracted - Fortran
1960's - control structures were abstracted - Algol
1970's - data structures were abstracted - Pascal, C
1980's - module interfaces were abstracted - Modula
1990's - abstraction of objects - C++, Java

As the decades progressed, higher level concepts were
abstracted into language features.

Where does Rexx fit in?  Since it has poor data structuring
capabilities, it fits into the 1960's.  OTOH, Object Rexx
fits nicely into the 1990's.

Since Perl has features that facilitate OOP, I'd place Perl
squarely in the 1990's.

Whether or not a language can be compiled down to machine
code is irrelevant, or at least fast becoming so.  Todays
personal computers are at least 3-4 orders of magnitude
faster than the first IBM PC.  Today's interpreted programs
run at least as fast, if not much faster, than the compiled
programs of yesterday.  In many cases, it's insignificant
anyways.  For example, in GUI programs, much of the work
happens in widget toolkit libraries anyways, and so there's
little performance advantage to compiling your program down
to machine code.

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com


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