Re: Shell Central

Re: Shell Central

[Christopher Browne]

In the last exciting episode, peter@abbnm.com (Peter da Silva) wrote::
> In article <42f85d82.0208290655.549f1e67@posting.google.com>,
> Ed Davis <ed_davis2@yahoo.com> wrote:
>> How about BUSH!
>> 
>> http://www.vaxxine.com/pegasoft/bush.html
>> 
>> It is sort of like BASH, but uses a subset of Ada as the
>> scripting language.
>
> Doesn't seem terribly well adapted to the UNIX paradigm of pipes and
> filters. It's more like a scripting language that defaults to "exec"
> for unknown commands. Useful, but not really a shell.

BUSH may be very simply characterized:

  It's about writing "scripts" in Ada.

Parallel it with REXX, which essentially provides a simplified version
of PL/1.

BUSH takes things a _bit_ further than REXX; it's apparently
sufficiently similar to the Parent Language that it is expected to be
relatively easy to modify scripts to make them compilable into plain
Ada code.
-- 
(concatenate 'string "cbbrowne" "@acm.org")
http://cbbrowne.com/info/scripting.html
Sturgeon's Law: 90% of *EVERYTHING* is crud.

Re: Shell Central

[John Brock]

In article <aknsli$1kb8df$1@ID-125932.news.dfncis.de>,
Christopher Browne  <cbbrowne@acm.org> wrote:
>In the last exciting episode, peter@abbnm.com (Peter da Silva) wrote::
>> In article <42f85d82.0208290655.549f1e67@posting.google.com>,
>> Ed Davis <ed_davis2@yahoo.com> wrote:

>>> How about BUSH!
>>> 
>>> http://www.vaxxine.com/pegasoft/bush.html
>>> 
>>> It is sort of like BASH, but uses a subset of Ada as the
>>> scripting language.

>> Doesn't seem terribly well adapted to the UNIX paradigm of pipes and
>> filters. It's more like a scripting language that defaults to "exec"
>> for unknown commands. Useful, but not really a shell.

>BUSH may be very simply characterized:
>
>  It's about writing "scripts" in Ada.
>
>Parallel it with REXX, which essentially provides a simplified version
>of PL/1.
>
>BUSH takes things a _bit_ further than REXX; it's apparently
>sufficiently similar to the Parent Language that it is expected to be
>relatively easy to modify scripts to make them compilable into plain
>Ada code.

BUSH looks far more elaborate than the sort of thing I was thinking
of, and I agree that it is not really a shell (nor is REXX for that
matter, although it would make a good shell for VM/CMS, if VM/CMS
had shells).  What about file expansion for example?  After browsing
the tutorial I didn't see how to do something like "ls *.txt".
The language I have in mind would *feel* like a shell, and share
a number of conventions with the bourne shell family, even though
some things would be quite different.

But BUSH does seem to be an example of something I have always
thought should be more common: a language intended from the beginning
to give user the option of either compiling or interpreting.  IBM
actually did have a REXX compiler on VM/CMS, which speeded up
execution by a factor of up to 10.  At the time I used it the
compiler didn't support the "interpret" instruction, but I believe
that was added later.  Anyway, this is such a useful feature that
I wonder why it isn't more common?
-- 
John Brock
jbrock@panix.com

Re: Shell Central

[Peter da Silva]

In article <akoadu$l64$1@panix3.panix.com>,
John Brock <jbrock@panix.com> wrote:
> The language I have in mind would *feel* like a shell, and share
> a number of conventions with the bourne shell family, even though
> some things would be quite different.

Have you had a look at the Plan 9 shell, "rc". It has a lot of feel
of the bourne shell, but the scripting is quite different and a lot
more regular.

It's also designed to be used cleanly from a window system, for example
the default prompt is a ";" so you can almost always cut-and-paste a few
lines of commands and they'll do the right thing.

-- 
I've seen things you people can't imagine. Chimneysweeps on fire over the roofs
of London. I've watched kite-strings glitter in the sun at Hyde Park Gate.  All
these things will be lost in time, like chalk-paintings in the rain.   `-_-'
Time for your nap.  | Peter da Silva | Har du kramat din varg, idag?    'U`

Re: Shell Central

[John Brock]

In article <akolbm$595@web.eng.baileynm.com>,
Peter da Silva <peter@abbnm.com> wrote:
>In article <akoadu$l64$1@panix3.panix.com>,
>John Brock <jbrock@panix.com> wrote:
>> The language I have in mind would *feel* like a shell, and share
>> a number of conventions with the bourne shell family, even though
>> some things would be quite different.

>Have you had a look at the Plan 9 shell, "rc". It has a lot of feel
>of the bourne shell, but the scripting is quite different and a lot
>more regular.
>
>It's also designed to be used cleanly from a window system, for example
>the default prompt is a ";" so you can almost always cut-and-paste a few
>lines of commands and they'll do the right thing.

Interesting!  I hadn't looked at this carefully, and I should.
It's still not exactly what I want, but it's closer than anything
I have run into so far.

They're still developing Plan 9!  How nice!
-- 
John Brock
jbrock@panix.com

Re: Shell Central

[Shmuel (Seymour J.) Metz]

In <aknsli$1kb8df$1@ID-125932.news.dfncis.de>, on 08/30/2002
   at 01:41 PM, Christopher Browne <cbbrowne@acm.org> said:

>Parallel it with REXX, which essentially provides a simplified
>version of PL/1.

No. The semantics of REXX are very different from those of PL/I, and
trying to use it as if it were a simplified PL/I will lead to some
nasty bugs. IMHO that was a mistake; it would have been better had
they syntax been a lot different of the semantics a lot closer.


-- 
     Shmuel (Seymour J.) Metz, SysProg and JOAT
     Atid/2, Team OS/2, Team PL/I

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Re: Shell Central

[John W. Kennedy]

Shmuel (Seymour J.) Metz wrote:
> No. The semantics of REXX are very different from those of PL/I, and
> trying to use it as if it were a simplified PL/I will lead to some
> nasty bugs. IMHO that was a mistake; it would have been better had
> they syntax been a lot different of the semantics a lot closer.

REXX was designed chiefly to be non-astonishing to non-programmers.  The
PL/I similarities are no more significant than the similarities between
C and PERL.

-- 
John W. Kennedy
Those in the seat of power oft forget their failings and seek only the
obeisance of others!  Thus is bad government born!  Hold in your heart
that you and the people are one, human beings all, and good government
shall arise of its own accord!  Such is the path of virtue!
-- Kazuo Koike, "Lone Wolf and Cub:  Thirteen Strings" (tr. Dana Lewis)

Re: Shell Central

[Shmuel (Seymour J.) Metz]

In <3D73B04C.4030207@attglobal.net>, on 09/02/2002
   at 02:39 PM, "John W. Kennedy" <jwkenne@attglobal.net> said:

>REXX was designed chiefly to be non-astonishing to non-programmers. 
>The PL/I similarities are no more significant than the similarities
>between C and PERL.

The syntax of REXX is superficially a lot closer to PL/I than the
syntax of PERL is to C. And regardless of the intent, the effect is to
trip up the PL/I programmer because of the things that look similar
but are very different.

-- 
     Shmuel (Seymour J.) Metz, SysProg and JOAT
     Atid/2, Team OS/2, Team PL/I

Any unsolicited commercial junk E-mail will be subject to legal
action.  I reserve the right to publicly post or ridicule any
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Re: Shell Central

[John Brock]

In article <3d72b4c2$1$fuzhry+tra$mr2ice@news.patriot.net>,
Shmuel (Seymour J.) Metz <spamtrap@library.lspace.org.invalid> wrote:
>
>In <aknsli$1kb8df$1@ID-125932.news.dfncis.de>, on 08/30/2002
>   at 01:41 PM, Christopher Browne <cbbrowne@acm.org> said:

>>Parallel it with REXX, which essentially provides a simplified
>>version of PL/1.

>No. The semantics of REXX are very different from those of PL/I, and
>trying to use it as if it were a simplified PL/I will lead to some
>nasty bugs. IMHO that was a mistake; it would have been better had
>they syntax been a lot different of the semantics a lot closer.

Can you give us some examples?  What mistakes could have been
corrected, and how might REXX have been improved by being less
different from PL/1 than it is.  I'm not arguing the point, I'm
just curious.
-- 
John Brock
jbrock@panix.com

Re: Shell Central

[Shmuel (Seymour J.) Metz]

In <al3pt6$7ph$1@panix3.panix.com>, on 09/03/2002
   at 10:07 PM, jbrock@panix.com (John Brock) said:

>Can you give us some examples?

The ones that seem to cause the most confusion are abutment, CALL,
SIGNAL and uninitialized variables.

>What mistakes could have been
>corrected, and how might REXX have been improved by being less
>different from PL/1 than it is.

IMHO it would have been cleaner to carry over the control structures
of PL/I intact.

Where I may trigger a flame war is that I like abutment and the
ability to use uninitialized variables as though they were constants
of the (upper case) same value as the name. I consider them to be
reasonable differences, despite the confusion. Others consider them to
be bad form. "NOVALUE" suggests that I may be in the minority.

-- 
     Shmuel (Seymour J.) Metz, SysProg and JOAT
     Atid/2, Team OS/2, Team PL/I

Any unsolicited commercial junk E-mail will be subject to legal
action.  I reserve the right to publicly post or ridicule any
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Re: Shell Central

[Peter Flass]

I definitely agree about CALL.  I still try to avoid CALL in favor of
function references because the syntax is such a bad joke.  Abutment,
not having a similarity in PL/I didn't cause any problems for me; I
mostly use || anyhow, and explicitly concatenate desired spaces.
SIGNAL is different enough that I don't have a problem with it.  I do
wish it had been GOTO when used for that purpose though; I don't think
SIGNAL is clear enough on what it's doing.

My biggest problem is having to put a comma at the end of lines being
continued.  I'm not used to it, and it's hard to see on the screen,
especially when what's being continued is a comma-separated list.  I'd
rather see semicolons as line delimiters, or '\' for continuation as in
C, or almost anything else.

"Shmuel (Seymour J.) Metz" wrote:
> 
> In <al3pt6$7ph$1@panix3.panix.com>, on 09/03/2002
>    at 10:07 PM, jbrock@panix.com (John Brock) said:
> 
> >Can you give us some examples?
> 
> The ones that seem to cause the most confusion are abutment, CALL,
> SIGNAL and uninitialized variables.