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From: 😜 <sorosj@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] rc's shortcomings (new subject line)
Date: Tue,  4 Sep 2012 19:27:36 +0200	[thread overview]
Message-ID: <50463A08.7050204@gmail.com> (raw)
In-Reply-To: <CAEoi9W5bZE+coAaQA-Be4P_JQoB6TR31GS=gYhq=6BhHNXCRKw@mail.gmail.com>

Hi, just my 2¢ for the fanning out of pipes: if I remember correctly,
mycroftiv's hubfs (or some other software in his contrib) allowed one to
do exactly this.
hth

On 08/28/2012 09:41 PM, Dan Cross wrote:
> On Tue, Aug 28, 2012 at 8:56 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>>> And rc is not perfect.  I've always felt like the 'if not' stuff was a kludge.
>>
>> no, it's certainly not.  (i wouldn't call if not a kludge—just ugly.
> 
> Kludge perhaps in the sense that it seems to be to work around an
> issue with the grammar and the expectation that it's mostly going to
> be used interactively, as opposed to programmatically.  See below.
> 
>> the haahr/rakitzis es' if makes more sense, even if it's wierder.)
> 
> Agreed; es would be an interesting starting point for a new shell.
> 
>> but the real question with rc is, what would you fix?
> 
> I think in order to really answer that question, one would have to
> step back for a moment and really think about what one wants out of a
> shell.  There seems to be a natural conflict a programming language
> and a command interpreter (e.g., the 'if' vs. 'if not' thing).  On
> which side does one err?
> 
>> i can only think of a few things around the edges.  `{} and $ are
>> obvious and is some way to use standard regular expressions.  but
>> those really aren't that motivating.  rc does enough.
> 
> I tend to agree.  As a command interpreter, rc is more or less fine as
> is.  I'd really only feel motivated to change whatever people felt
> were common nits, and there are fairly few of those.
> 
>> perhaps (let's hope) someone else has better ideas.
> 
> Well, something off the top of my head: Unix pipelines are sort of
> like chains of coroutines.  And they work great for defining linear
> combinations of filters.  But something that may be interesting would
> be the ability to allow the stream of computations to branch; instead
> of pipelines being just a list, make them a tree, or even some kind of
> dag (if one allows for the possibility of recombining streams).  That
> would be kind of an interesting thing to play with in a shell
> language; I don't know how practically useful it would be, though.
> 
>>> switch/case would make helluva difference over nested if/if not, if
>>> defaulted to fall-through.
>>
>> maybe you have an example?  because i don't see that.  if not works
>> fine, and can be nested.  case without fallthrough is also generally
>> what i want.  if not, i can make the common stuff a function.
>>
>>> variable scoping (better than subshel) would help writing larger
>>> scripts, but that's not necessarily an improvement ;-) something
>>> similar to LISP's `let' special form, for dynamic binding.
> 
> (A nit: 'let' actually introduces lexical scoping in most Lisp
> variants; yes, doing (let ((a 1)) ...) has non-lexical effect if 'a'
> is a dynamic variable in Common Lisp, but (let) doesn't itself
> introduce dynamic variables.  Emacs Lisp is a notable exception in
> this regard.)
> 
>> there is variable scoping.  you can write
>>
>>         x=() y=() cmd
>>
>> cmd can be a function body or whatever.  x and y are then private
>> to cmd.  you can nest redefinitions.
>>
>>         x=1 y=2 {echo first $x $y; x=a y=b {echo second $x $y; x=α y=β {echo third $x $y}; echo ret second $x $y}; echo ret first $x $y}
>>         first 1 2
>>         second a b
>>         third α β
>>         ret second a b
>>         ret first 1 2
> 
> This syntax feels clunky and unfamiliar to me; rc resembles block
> scoped languages like C; I'd rather have a 'local' or similar keyword
> to introduce a variable in the scope of each '{ }' block.
> 
>> you should try the es shell.  es had let and some other scheme-y
>> features.  let allows one to do all kinds of tricky stuff, like build
>> a shell debugger in the shell, but my opinion is that es was more
>> powerful and fun, but it didn't buy enough because it didn't really
>> expand on the essential nature of a shell.  what can one do to
>> manipulate processes and file descriptors.
> 
> es was a weird merger between rc's syntax and functional programming
> concepts.  It's neat-ish, but unless we're really ready to go to the
> pipe monad (not that weird, in my opinion) you're right.  Still, if it
> allowed one to lexically bind a file descriptor to a variable, I could
> see that being neat; could I have a closure over a file descriptor?  I
> don't think the underlying process model is really set up for it, but
> it would be kind of cool: one could have different commands consuming
> part of a stream in a very flexible way.
> 
>         - Dan C.
> 



  parent reply	other threads:[~2012-09-04 17:27 UTC|newest]

Thread overview: 133+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-28  8:57 [9fans] rc vs sh Rudolf Sykora
2012-08-28  9:47 ` hiro
2012-08-28  9:52 ` dexen deVries
2012-08-28 10:27   ` Rudolf Sykora
2012-08-28 13:07   ` Lucio De Re
2012-08-28 13:40     ` Rudolf Sykora
2012-08-28 14:10       ` Lucio De Re
2012-08-28 14:13         ` Kurt H Maier
2012-08-28 14:52           ` Lucio De Re
2012-08-28 15:05             ` Kurt H Maier
2012-08-28 15:18               ` Dan Cross
2012-08-28 15:30                 ` Kurt H Maier
2012-08-28 15:45                   ` Dan Cross
2012-08-28 17:43                     ` Kurt H Maier
2012-08-28 18:20                       ` Dan Cross
2012-08-28 18:26                         ` Kurt H Maier
2012-08-28 18:39                           ` Dan Cross
2012-08-28 18:47                             ` Kurt H Maier
2012-08-28 20:42                             ` Jeremy Jackins
2012-08-28 21:20                               ` Dan Cross
2012-08-28 20:40                   ` Uriel
2012-08-28 15:36               ` Lucio De Re
2012-08-28 15:35                 ` Kurt H Maier
2012-08-28 15:41                   ` erik quanstrom
2012-08-28 15:47                     ` Kurt H Maier
2012-08-28 16:04                       ` hiro
2012-08-28 16:05                   ` Lucio De Re
2012-08-28 17:46                     ` Kurt H Maier
2012-08-28 18:19                       ` Lucio De Re
2012-08-28 18:18                         ` Kurt H Maier
2012-08-28 20:44                   ` Uriel
2012-08-31 22:24                     ` Kurt H Maier
2012-08-31 23:00                       ` Uriel
2012-08-31 23:15                         ` hiro
2012-08-31 23:56                           ` Matthew Veety
2012-09-02 15:20                             ` suharik
     [not found]                             ` <CAF9FGtS9xYBNzneNPs2eBkkqVGzn5V0FjdEWDYs_EaUu0waRvQ@mail.gmail.c>
2012-09-02 17:25                               ` erik quanstrom
2012-09-02 20:40                                 ` suharik
2012-09-03  7:31                                 ` Rudolf Sykora
2012-09-03  8:22                                   ` dexen deVries
2012-09-03 10:04                                   ` suharik
2012-09-03 10:57                                     ` hiro
     [not found]                                 ` <CAF9FGtRdcFuuefr4q0zFBrkwaQ5a_-w4J-=xqo-MYp+phjQBaA@mail.gmail.c>
2012-09-03 13:42                                   ` erik quanstrom
     [not found]                                 ` <CAF9FGtTFskxpVd_CxGEKpRwfSihVjyREqWwFCmjiWksCKZoDvg@mail.gmail.c>
2012-09-03 13:46                                   ` erik quanstrom
2012-10-25 13:36                                     ` Ethan Grammatikidis
2012-10-25 13:48                                       ` erik quanstrom
2012-09-03  8:32                         ` Balwinder S Dheeman
2012-08-28 16:06             ` tlaronde
2012-08-28 16:12               ` Aram Hăvărneanu
2012-08-28 16:32                 ` tlaronde
2012-08-28 20:43                 ` tlaronde
2012-08-28 18:13               ` Lucio De Re
2012-08-30  6:14                 ` arnold
2012-08-30  7:41                   ` Lucio De Re
2012-08-30  9:34                     ` tlaronde
2012-08-30 10:26                       ` Lucio De Re
2012-08-30 10:29                         ` tlaronde
2012-08-30 10:50                           ` Lucio De Re
2012-08-30 10:35                         ` Dan Cross
2012-08-28 14:16         ` erik quanstrom
2012-08-28 14:58           ` Lucio De Re
2012-08-28 14:16         ` dexen deVries
2012-08-28 14:23           ` hiro
2012-08-28 14:34             ` hiro
2012-08-29  9:16   ` Balwinder S Dheeman
2012-08-29 15:10     ` Charles Forsyth
2012-08-29 15:22       ` hiro
2012-08-29 15:34         ` Charles Forsyth
2012-10-25 13:45       ` Ethan Grammatikidis
2012-10-25 13:56       ` dexen deVries
2012-08-28 15:09 ` Dan Cross
     [not found] ` <CAEoi9W6K07ZgNS+7-oeQY3dkedW7qZLnOh79m5J7KCw7os5aEQ@mail.gmail.c>
2012-08-28 15:26   ` erik quanstrom
2012-08-28 15:40     ` Lucio De Re
2012-08-28 15:34       ` erik quanstrom
2012-08-28 18:24     ` dexen deVries
2012-08-28 18:44       ` [9fans] rc's shortcomings (new subject line) erik quanstrom
2012-08-28 19:34         ` dexen deVries
2012-08-29  0:06           ` arisawa
2012-08-29  8:12             ` dexen deVries
2012-08-28 19:41         ` Dan Cross
2012-08-28 20:14           ` Bakul Shah
2012-08-29  1:39             ` erik quanstrom
2012-08-29  1:43               ` erik quanstrom
2012-08-29  2:13               ` Bakul Shah
2012-08-29  2:23                 ` erik quanstrom
2012-08-29  2:44                   ` Bakul Shah
2012-08-29  4:28                     ` erik quanstrom
2012-08-28 20:31           ` Aram Hăvărneanu
2012-09-04 17:27           ` 😜 [this message]
2012-08-28 19:53         ` Bakul Shah
     [not found]         ` <CAEoi9W5bZE+coAaQA-Be4P_JQoB6TR31GS=gYhq=6BhHNXCRKw@mail.gmail.c>
2012-08-28 20:34           ` erik quanstrom
2012-08-28 22:46             ` Bakul Shah
2012-08-29  1:28               ` erik quanstrom
2012-08-29  8:09             ` dexen deVries
2012-08-29  8:38             ` Dan Cross
     [not found]             ` <CAEoi9W5_r=4w5EcdrbKuqD566p=C5KvEEHg72YKzdat18En2-w@mail.gmail.c>
2012-08-29 13:57               ` erik quanstrom
2012-08-29 15:07                 ` Charles Forsyth
2012-08-30 10:05                 ` Dan Cross
2012-08-30 10:43                   ` Charles Forsyth
2012-08-30 13:41                   ` dexen deVries
2012-08-30 13:47                     ` erik quanstrom
2012-08-30 14:26                       ` dexen deVries
2012-08-30 14:29                         ` erik quanstrom
2012-08-30 14:24                     ` Dan Cross
     [not found]                     ` <CAEoi9W6NL-zGryJnMrAX3B77bk1bOEMfkv_R7M4W052LZR4yrg@mail.gmail.c>
2012-08-30 14:26                       ` erik quanstrom
2012-08-30 14:33                         ` Dan Cross
     [not found]                         ` <CAEoi9W45W0pK7MA2FvxsCVCuRcqw-JxOiEn+JQtWMo0rFcSEpg@mail.gmail.c>
2012-08-30 14:41                           ` erik quanstrom
2012-08-30 14:48                             ` dexen deVries
2012-08-30 15:11                               ` sl
2012-08-30 15:13                               ` Lucio De Re
2012-08-30 15:07                                 ` Burton Samograd
2012-08-30 15:13                                 ` Charles Forsyth
2012-08-30 15:14                                   ` Charles Forsyth
2012-08-30 17:02                   ` Bakul Shah
2012-08-30 17:18                     ` erik quanstrom
2012-08-30 20:06                       ` Charles Forsyth
     [not found]                   ` <CAOw7k5jQxJCs64ZjrXp1mU0zTUTG6p7VXYX5ykwQ8OmFATLirg@mail.gmail.c>
2012-08-30 20:10                     ` erik quanstrom
     [not found]                 ` <CAEoi9W6c2JaxrTDwR76TjuN9DeBXnO6gueOGCaEh+Fksfb9zqQ@mail.gmail.c>
2012-08-30 13:33                   ` erik quanstrom
2012-08-30 14:21                     ` Dan Cross
2012-08-30 14:25                       ` Dan Cross
2012-08-30 14:45                     ` Charles Forsyth
2012-08-30 14:55                       ` Charles Forsyth
     [not found]                   ` <CAEoi9W5AagpdK4aZCYs5tSMESU3yoMe9bmgX3GcphTcYuMq9kQ@mail.gmail.c>
2012-08-30 14:34                     ` erik quanstrom
2012-08-30 14:44                     ` erik quanstrom
     [not found]                   ` <CAOw7k5i-JO=bOS8h+S0zdWghCWhSN36uFebMYnzvs=fdNQgA+g@mail.gmail.c>
2012-08-31  1:33                     ` erik quanstrom
2012-10-25 14:56 ` [9fans] rc vs sh Ethan Burns
2012-10-25 15:08   ` hiro
2012-10-25 17:02     ` Gorka Guardiola
2012-10-25 17:18       ` Matthew Veety
2012-10-25 17:26         ` John Floren
2012-10-25 19:03           ` hiro
2012-10-25 19:08     ` Skip Tavakkolian
2012-08-30 15:24 [9fans] rc's shortcomings (new subject line) Lucio De Re

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