Re: [racket-users] Sending a file via HTML request.

['John Clements' via Racket Users]

> On Aug 24, 2016, at 4:36 AM, Normal Loone  wrote:
> 
> Sorry, I should have been clearer:
> 
> I want to send a file directly from DrRacket to a server. I have submit 
> button as a plugin in DrRacket and it then should take the file and send it 
> to the server (the file is known, doesnt need to be selected from user).
> 
> I tried the code from HTH Stephen, but problem is that the web application 
> starts on DrRacket start and not when I press the button, how I wanted it.
> 
> So if someone could tell me a way to just directly send a file with DrRacket 
> as an HTML request, I'd really appreciate that.

Yes, this is a one-liner:

#lang racket

(require net/http-client)

(http-sendrecv #"example.com"
   #"/"
   #:method "POST"
   #:data "MY FAVORITE BYTES”)

This will send a POST request to example.com, with path /, and attach the bytes 
#”MY FAVORITE BYTES”.

John Clements


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Re: [racket-users] warnings for requiring opaque types in typed racket 6.6

[Matthew Eric Bassett]

On 08/24/2016 02:28 PM, Alex Knauth wrote:
> That's the short-term solution. A better solution would be for typed racket 
> to implement a different version of #:opaque that would actually wrap the 
> values in opaque structs when they flow from untyped-to-typed and unwrap them 
> when they flow from typed-to-untyped. That way typed racket would know how to 
> protect the values.

we will be eagerly awaiting such a change to typed racket, as unsafe
requires are worrisome.   If a lay-programmer could contribute do let me
know, though I am not sure I know where to start.

-- 
Matthew Eric Bassett | http://mebassett.info

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[racket-users] [ANN] A type-expander library for Typed/Racket

[Dupéron Georges]

Based on Asumu's work on type expanders 
(https://github.com/racket/racket/compare/master...takikawa:tr-type-expander), 
I have written a library which adds support for type expanders in typed/racket. 
Type expanders are to types what match expanders are to match patterns. A type 
expander is a special macro which can appear wherever a type would normally be 
expected, and must expand to a type.

The library is written using literate programming, with (a variant of) 
scribble/lp2. The annotated source code is available here:
http://docs.racket-lang.org/type-expander.hl/
and the documentation here:
http://docs.racket-lang.org/type-expander/

This library comes along with the multi-id library 
(http://docs.racket-lang.org/multi-id/, literate source: 
http://docs.racket-lang.org/multi-id.hl/), which allows easy definition of an 
identifier which acts as a type expander, match expander, normal macro and 
identifier macro. It can be used to define new datatypes, where a single 
identifier represents the type, match clause, literal
instance as in (foo-datatype 1 2 3), and constructor function as in (map 
foo-datatype …).

The type-expander library is in beta status:
* It works well and I have been using it for a while without issues.
* The API should not change significantly in the future.
* However, there are many typed/racket primitives which are not
  overloaded yet, as noted in the documentation (patches are welcome).
* Also, a couple of features are missing (patches are welcome again):
   * The special form `Let`, which acts like `let-syntax` for types,
 is only partially implemented.
   * The special form `(Λ (stx) . body)`, which acts as an anonymous
 type expander, is not implemented at all.
   * There is no syntax-local-type-introduce.

Any feedback is appreciated! :)

Regards,
Georges Dupéron

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Re: [racket-users] Re: Sending a file via HTML request.

[George Neuner]

I posted to this thread yesterday through Gmane, but I see it hasn't yet 
appeared.  Posting through Gmane has been flaky lately - I'm sending 
this updated version via email.Not sure what's happening with 
Gmane.  Apologies if you see things multiple times.


George




On 8/24/2016 7:36 AM, Normal Loone wrote:

Sorry, I should have been clearer:

I want to send a file directly from DrRacket to a server. I have submit button 
as a plugin in DrRacket and it then should take the file and send it to the 
server (the file is known, doesnt need to be selected from user).

I tried the code from HTH Stephen, but problem is that the web application 
starts on DrRacket start and not when I press the button, how I wanted it.

So if someone could tell me a way to just directly send a file with DrRacket as 
an HTML request, I'd really appreciate that.



On Tue, 23 Aug 2016 02:09:24 -0700 (PDT), Normal Loone
 wrote:

>Yeah, my main problem is how do I pack the file into a JSON Object
>and then send it?

Just FYI: JSON is a printable coding, so any non-printable characters
in a binary file must be escaped - making the transfer larger.

The read-json and write-json functions take care of escaping, but if
you are sending large files, the conversion overhead may be significant.

Note that converting an arbitrary binary file to JSON is convoluted -
JSON is meant to handle character strings, not bytes.  You have
to do something like:

(string->jsexpr  (bytes->string/utf-8  file-bytes))

which is a problem if the file is very large as the file data and converted
string both need to be in memory.  It's possible to send a file in pieces
and reassemble it at the receiver, but that can get quite complicated.


>With (require net/http-client) I could already establish a connection
>with (http-conn-sendrecv! hc uri), but All I can send is the empty
>header of the http request.
>
>How do I add the HTML code or the file in the json object within it?

If the data is JSON encoded, you can send it as an HTTP string
parameter: e.g.,

(require net/http-client
 net/uri-codec)

(let [
  (params
   (alist->form-urlencoded
(list (cons 'file  json-encoded-data ))
  )))
  (headers
   (list "Content-Type: application/x-www-form-urlencoded")
   )
 ]

  (let-values
  [
   ((resp-code resp-hdrs port)
(http-sendrecv host
   url
   #:method #"POST"
   #:data params
   #:headers headers
   ))
  ]
(printf "~s~n~s~n~s~n"
resp-code
resp-hdrs
(port->bytes port))
   ))

The print at the end is displaying the server's response.


There is a limit  - which I can't recall at the moment - to the size of
simple upload forms, so you might have trouble sending a long
file this way.

Large uploads, binary data uploads, and piecemeal incremental
uploads are meant to be done using multipart forms.

Multipart forms are complex to encode: they have opening headers,
boundary markers enclosing and sometimes interspersed with the
data, and closing footers after the data.

I don't have a ready example. For more information see
http://www.rfc-base.org/rfc-1867.html

Hope this helps,
George


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Re: [racket-users] Re: Sending a file via HTML request.

[Stephen Chang]

Vishesh Yadav wrote a DrRacket plugin that automatically compiles a
program to JS via whalesong and uploads it to a server. It sounds
related to what you are describing so you may want to take a look at
his code.

The plugin code is here: https://github.com/vishesh/drracket-whalesong
in particular these lines may be of interest:
https://github.com/vishesh/drracket-whalesong/blob/master/tool.rkt#L62-L74

and the server code is here: https://github.com/vishesh/whalebin

If you want to try it out, the server is running at
bigbang.ccs.neu.edu (but seems to be experiencing temporary problems
at the moment).

On Wed, Aug 24, 2016 at 7:36 AM, Normal Loone  wrote:
> Sorry, I should have been clearer:
>
> I want to send a file directly from DrRacket to a server. I have submit 
> button as a plugin in DrRacket and it then should take the file and send it 
> to the server (the file is known, doesnt need to be selected from user).
>
> I tried the code from HTH Stephen, but problem is that the web application 
> starts on DrRacket start and not when I press the button, how I wanted it.
>
> So if someone could tell me a way to just directly send a file with DrRacket 
> as an HTML request, I'd really appreciate that.
>
> --
> You received this message because you are subscribed to the Google Groups 
> "Racket Users" group.
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> email to racket-users+unsubscr...@googlegroups.com.
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Re: [racket-users] warnings for requiring opaque types in typed racket 6.6

[Matthew Eric Bassett]

thank you for your reply, Alex.  That was informative and helpful.

On 08/19/2016 02:56 PM, Alex Knauth wrote:
> So to work around that, you can use `define-new-subtype` along with 
> `unsafe-require/typed`.
> 
> #lang typed/racket
> (require typed/racket/unsafe)
> (define-new-subtype My-Type (make-my-type My-Type))
> (unsafe-require/typed "untyped.rkt" [my-type? (-> Any Boolean : My-Type)] 
> [my-type My-Type])
> 

This is quite wonky and the warnings in the Typed Racket docs about
unsafe make me very wary about using such stuff in production.  Can the
others confirm if this is indeed the desired behavior or something that
might be fixed in a later version?

Regards,

M.e.




> 
> Alex Knauth
> 
>> Hi all,
>>
>> I note that Racket 6.6 now issues warnings for certain generated
>> contracts in typed/untyped interactions.  In particular, these warnings
>> come up when requiring an untyped file from a typed file.  For example,
>> say I have
>>
>> test.rkt:
>> -
>> #lang racket
>>
>>
>> (define my-type
>> (let ()
>>  (struct my-type () )
>>  (my-type)))
>> (define (my-type? x)
>> (eq? x my-type))
>>
>>
>> (provide my-type? my-type)
>>
>> And follow that with type interactions:
>>
>> $ racket -I typed/racket
>> Welcome to Racket v6.6.
>> -> (require/typed "test.rkt" [#:opaque My-Type my-type?] [my-type My-Type])
>> my-type?: contract violation
>>  any-wrap/c: Unable to protect opaque value passed as `Any`
>>  value: #
>>  This warning will become an error in a future release.
>>  in: the 1st argument of
>>  a part of the or/c of
>>  (or/c
>>   struct-predicate-procedure?/c
>>   (-> Any boolean?))
>>  contract from: (interface for my-type?)
>>  blaming: top-level
>>   (assuming the contract is correct)
>>  at: readline-input:1.44
>>
>> I use a similar pattern to call the untyped db library from typed code,
>> say with
>> (require/typed db [#:opaque Sql-Null] [sql-null Sql-Null]), which would
>> bring up a similar warning.
>>
>> Is there a "correct" way to handle these sorts of cases?
>>
>> Thanks!
>>
>> Matthew Eric
>>
>> -- 
>> Matthew Eric Bassett | http://mebassett.info
> 
> 

-- 
Matthew Eric Bassett | http://mebassett.info

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Re: [racket-users] Using the base language’s get-info function with make-meta-reader

[Alex Knauth]

> On Aug 24, 2016, at 2:05 AM, Alexis King  wrote:
> 
> When using make-meta-reader from syntax/module-reader, is it possible
> to access the “base” language’s get-info function from within the
> read or read-syntax wrapping functions? I’d like to adjust how a
> particular meta language is read based on a property on the base
> language.

A month or so ago I started work on a version of make-meta-reader that would 
allow this, but I got caught up in the 
I-have-no-idea-what-it's-supposed-to-be-doing of it. Matthew Flatt answered the 
first question I had about what the second argument was, but then I had other 
things to do and I never finished it.

If I have more time in the next 2 weeks I could look at it again...

Alex Knauth

> Currently, my guess is the answer is a fairly flat “no”, but I
> figured I’d ask in case I was missing something.


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[racket-users] Re: Sending a file via HTML request.

[Normal Loone]

Sorry, I should have been clearer:

I want to send a file directly from DrRacket to a server. I have submit button 
as a plugin in DrRacket and it then should take the file and send it to the 
server (the file is known, doesnt need to be selected from user).

I tried the code from HTH Stephen, but problem is that the web application 
starts on DrRacket start and not when I press the button, how I wanted it.

So if someone could tell me a way to just directly send a file with DrRacket as 
an HTML request, I'd really appreciate that.

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[racket-users] Using the base language’s get-info function with make-meta-reader

[Alexis King]

When using make-meta-reader from syntax/module-reader, is it possible
to access the “base” language’s get-info function from within the
read or read-syntax wrapping functions? I’d like to adjust how a
particular meta language is read based on a property on the base
language.

Currently, my guess is the answer is a fairly flat “no”, but I
figured I’d ask in case I was missing something.

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