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<  Erlang questions mailing list  ~  Comments on the www.erlang.org course.

bhyde at pobox.com
Posted: Wed Feb 10, 1999 5:46 pm Reply with quote
Guest
I've recently read thru the course that get's top billing at
www.erlang.org. Here are a few typos and questions. - ben

---

** Sequential Programming
typo: This lesson is missing one last 'back to top' button.
question: What's the unicode, utf-8 etc. etc. story today.
question: The string is a list implies that strings are not very dense?
question: Atoms are interned in a per node pool and never reclaimed, I presume.

*** Concurrent Programming

**** Client Server Model
typo: The code for request/1 uses the variable R rather than Rep by mistake.

*** Error Handling

**** Processes can trap exit signals.
drawo: The illustration ought to show P3 linked to P2 not sending a message to P2.

*** Advanced Topics
**** References
typo: The first sentence is not gramatical.
question: Is this the only use of the term "symbol", and why?

*** Obtaining System Information
Typo: "want to do this?" not "what to do this?"

** History
"Conclusion: The language must contain primitives for concurrency
and error recovery, and the execution model must not have back-tracking.
(Rules out Lisp and Prolog.)"
Since Lisp does not have backtracking I guess it's time to backtrace
and redo the entire project, eh?


Misc:
At this point in my climbing up the learning curve I was surprised
that the application module and the tangle around load, path, etc.
were not covered more.

The error handling section was very useful. A terse statement of
the exact coupling between exceptions, exit signals, and the
error_handler would be nice.

You all have a very nice system here.

- ben


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joe at erix.ericsson.se
Posted: Thu Feb 11, 1999 12:48 pm Reply with quote
Guest
Hi Ben,
Thanks a lot, I fixed up the errors that you observed.

See below (and on the updated web site).


> I've recently read thru the course that get's top billing at
> www.erlang.org. Here are a few typos and questions. - ben

Thanks - we always like complements :-)

> ---
>
> ** Sequential Programming
> typo: This lesson is missing one last 'back to top' button.

fixed

> question: What's the unicode, utf-8 etc. etc. story today.

In the spec. Not yet implemented.


> question: The string is a list implies that strings are not very dense?

They take 8 bytes/character (is that what you meant?) Binaries
take 1 byte/character (asymptotically) - the overhead on small binaries
is << ask klacke, or tony >>

> question: Atoms are interned in a per node pool and never reclaimed, I presume.

Not specified. The current beam/jam does not garb the atom table.


>
> *** Concurrent Programming
>
> **** Client Server Model
> typo: The code for request/1 uses the variable R rather than Rep by mistake.

Fixed

>
> *** Error Handling
>
> **** Processes can trap exit signals.
> drawo: The illustration ought to show P3 linked to P2 not sending a message to P2.
>

Fixed (I *lost* the .fig file so this fix took a looooooooong time Sad)


> *** Advanced Topics
> **** References
> typo: The first sentence is not gramatical.
> question: Is this the only use of the term "symbol", and why?

Fixed - major! rewrite (panic on - the standardisation committee
doesn't really know what a reference is! - what happens if you store a
reference in a file and read the file a million years later? - what
happens to copies of references - what happens in parallel universes -
what happens in the year 2000 - panic off)

>
> *** Obtaining System Information
> Typo: "want to do this?" not "what to do this?"
>

Fixed

> ** History
> "Conclusion: The language must contain primitives for concurrency
> and error recovery, and the execution model must not have back-tracking.
> (Rules out Lisp and Prolog.)"
> Since Lisp does not have backtracking I guess it's time to backtrace
> and redo the entire project, eh?
>

Not fixed. Lisp was ruled out 'cos of lack of
concurrency not backtracking!

>
> Misc:
> At this point in my climbing up the learning curve I was surprised
> that the application module and the tangle around load, path, etc.
> were not covered more.

Ummm - that stuff (paths, loading etc.) is a "local issue" - the
course is (mostly) generic - although the boundary is not hard and fast.

>
> The error handling section was very useful. A terse statement of
> the exact coupling between exceptions, exit signals, and the
> error_handler would be nice.

The precise statement is not terse! - see the book for the exact
> coupling.

You all have a very nice system here. - ben

Thanks,

/Joe


--
Joe Armstrong Computer Science Laboratory +46 8 719 9452
AT2/ETX/DN/SU Ericsson Telecom SE-126 25 Stockholm Sweden
joe_at_cslab.ericsson.se http://www.ericsson.se/cslab/~joe






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