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5 points by rcoder 5938 days ago | link | parent | on: Show us your Arc code

For those who want a slightly less-complete webapp to use as a sample:

  (= fortune-bin-path* "/usr/games/fortune" page-title* "Read My Fortune")

  (def make-fortune-cookie ()
    (tostring (system fortune-bin-path*)))

  (defop fortune req
    (whitepage
      (tag h1 (link page-title* "fortune"))
      (br 2)
      (tag pre (pr (make-fortune-cookie)))
      (br 2)
      (tag small
        (link "[made with arc]" "http://arclanguage.org/"))))

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1 point by albertcardona 5938 days ago | link

For illustration, would you mind explaining how to connect this code to a web server.

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2 points by rcoder 5938 days ago | link

You don't have to connect it. Copy the above into a file called 'fortune.arc' inside your Arc source code directory, then type the following from an Arc REPL:

  (load "fortune.arc")
  (asv)
The 'asv' function spawns the built-in web server, as shown in the blog example.

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1 point by albertcardona 5935 days ago | link

Sometimes the program fails with the error below, on clicking on the link. A blank webpage is shown. After F5 (refresh), all back to normal.

Looks to me, that the system call fails because 'fortune' returns -1.

  date: 1202019843: No such file or directory
  make-string: expects argument of type <non-negative exact integer>; given -1

  === context ===
  subseq
  memodate
  srvlog
  gs899
  handle-request-thread

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2 points by rcoder 5938 days ago | link | parent | on: Lots of unrelated impressions of Arc

It's funny, because the with/let forms in Arc immediately struck me as quite sensible. Both include an implicit 'do', (or 'progn', for the crusty oldsters like me) and so need a bounded number of forms to scan for new bindings. In the case of a 'with' form, there could be any number of terms, to the parens around the list of forms are needed. The 'let' form, on the other hand, only binds a single identifier, so the first and second parameters to the form are always going to be the term name and value, respectively.

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1 point by serhei 5938 days ago | link

Yeah, that logic makes sense.

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4 points by rcoder 5938 days ago | link | parent | on: patch to fix (date) on linux

Here's an alternate version which uses the underlying mzscheme date-handling library; it's less "bootstrapped", but also supports formatting of arbitrary timestamps under Linux.

http://paste.lisp.org/display/55071

(Feel free to ignore the 'os-name' and 'chomp' functions added to arc.arc; they are obviously from an earlier variant of the function which used the same approach as @starc.)

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1 point by starc 5938 days ago | link

Thanks, that's much better than calling system.

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2 points by rcoder 5938 days ago | link

Agreed, though what I'd really like is a full time/date stack built in Arc...using the MzScheme primitives is pretty ugly for a supposedly "bootstrapped" language.

There are enough other areas where Arc is coupled to the underlying Scheme runtime, though, that it's probably not worth worrying about at this point.

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6 points by rcoder 5939 days ago | link | parent | on: Profiling?

You can use the built-in MzScheme profiling tools; just run '(time (tl))' instead of '(tl)' to start the Arc REPL. You'll want some way to force a return from the toplevel interpreter, which may mean writing a shutdown routine for the web listener that doesn't require Ctrl-C halting the server thread, but that should be easy enough to do.

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1 point by elibarzilay 5938 days ago | link

MzScheme has a better profiling facility (the errortrace collection), but using it without source information is not too helpful. It is possible to do that (and I have a patch that does it), but it's not a quick solution.

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2 points by rcoder 5939 days ago | link | parent | on: Arc as a better "common" Lisp?

Implementing lisp in PHP would be like trying to theme your Windows 98 system to look like OS X. Yes, it's theoretically possible, and would increase the number of pieces of hardware on which your pretty UI could run, but it pretty much defeats the point of working in a Lisp to begin with.

You'd also give up the rich set of libraries and add-ons that are the real only argument for PHP.

Plus, there's the fact that the built-in Arc application server assumes a persistent, threaded server process is running throughout the lifespan of your application. PHP scripts are a one-shot deal; any local state is thrown away after each page request unless you explicitly serialize it to the session, database, or another persistent store.

Now, if you want a different surface syntax atop PHP, that's another question entirely. You certainly couldn't do much worse than what's there now.

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1 point by andreyf 5938 days ago | link

the rich set of libraries and add-ons that are the real only argument for PHP.

The other argument being that you can run PHP on just about any shared host out there.

Plus, there's the fact that the built-in Arc application server assumes a persistent, threaded server process is running throughout the lifespan of your application. PHP scripts are a one-shot deal...

Nobody said it was easy, but is it possible?

I guess what it comes down to is that anyone using a shared host isn't really "serious" enough to be writing an app in Arc to begin with.

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1 point by rcoder 5938 days ago | link

> Nobody said it was easy, but is it possible?

Of course it's possible. The question is whether it's a worthwhile use of valuable hacking time.

I also don't suspect it's a particularly interesting problem for the people most likely to be able to tackle it effectively. Now, a native Arc compiler for x86/AMD64, that would be a nice widget to have.

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1 point by apotheon 5938 days ago | link

Wanna bet? I know a bunch of people using shared hosting (for economic reasons) who would probably love to use Arc.

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2 points by treef 5939 days ago | link

har har!

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4 points by rcoder 5939 days ago | link | parent | on: Welcome

Having fun hacking with it so far, but I thought I'd bring up one compatibility glitch that hit me early on:

The definition of 'date' in arc.arc assumes a BSD-compatible 'date' binary on the host system. Unfortunately, the allowed arguments for GNU date are quite different. AFAICT, it is in fact impossible to convert the epoch-seconds timestamp format into a formatted date using the GNU version of the utility. Since the bundled web server uses the 'date' function to generate logfile names, any attempt to run a webapp on Linux immediately blows up.

I've hacked up a new implementation at the MzScheme layer using native date structs, but it would probably be worth porting a more complete date/time logic library to Arc, and relying on something like a native 'current-milliseconds' call only.

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