As to (@ data 'COMPANY), I've considered and used exactly that simply by
(define @ hash-ref). And it's not bad because it's shorter. It's just not
as good as (data 'COMPANY).
I do notice that the Clojure folks decided that dictionaries were functions
such that
(def talk { "cow" "moo" "dog" "bark" })
can be treated in function position.
(talk "cow")
I'll be looking at the #%app idea in a bit.
------
John Griffin, CTO
IT Talent Team, LLC
www.ittalentteam.com
855-488-8326
On Aug 5, 2013, at 12:00 PM, users-requ...@racket-lang.org wrote:
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> Today's Topics:
>
> 1. Re: (procedure? (hash)) -> true (Tony Garnock-Jones)
> 2. Re: (procedure? (hash)) -> true (Matthias Felleisen)
> 3. issue with Dr Racket in linux platform. (Vikas Sood)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 05 Aug 2013 11:39:06 -0400
> From: Tony Garnock-Jones <to...@ccs.neu.edu>
> To: John Griffin <j...@ittalentteam.com>, racket-users
> <users@racket-lang.org>
> Subject: Re: [racket] (procedure? (hash)) -> true
> Message-ID: <51ffc71a.8080...@ccs.neu.edu>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 08/05/2013 11:30 AM, John Griffin wrote:
>> Thanks in advance for any advice leading to more succinct hash access.
>
> Had you considered something along the lines of
>
> (define (handier-style data)
> (when (@ data 'COMPANY)
> (db-exec ... (@ data 'COMPANY))))
>
> ?
>
> You might start from
>
> (define (@ base . path)
> (match path
> ['() base]
> [(cons (? number? n) rest)
> (apply @ (list-ref base n) rest)]
> [(cons (? symbol? k) rest)
> (apply @ (hash-ref base k) rest)]
> [... maybe other things ...]))
>
> to give yourself a not-quite-XPath-like means of projecting JSON values.
>
> Interesting design decisions include: what to do when a list index is
> out of range, or a hash key is not present? (Error? Terminate early
> returning some kind of "undefined" value?)
>
> Cheers,
> Tony
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 5 Aug 2013 11:52:49 -0400
> From: Matthias Felleisen <matth...@ccs.neu.edu>
> To: John Griffin <j...@ittalentteam.com>
> Cc: users@racket-lang.org
> Subject: Re: [racket] (procedure? (hash)) -> true
> Message-ID: <b4e00c63-e999-46a0-8478-9dc978698...@ccs.neu.edu>
> Content-Type: text/plain; charset="windows-1252"
>
>
> Consider overriding #%app for your modules. And
>
> (define (curt-style-receiver data)
> (cond
> [(data 'COMPANY) => (curry db-exec ...)]
> [else .. what are you doing in the #f case? nothing? ...]))
>
>
> On Aug 5, 2013, at 11:30 AM, John Griffin wrote:
>
>> I do a lot of work with hash as the result of JSON-RPC calls, with
>> considerable use of hash-ref. In most places, I've replaced the hash with
>> a local result of transforming the hash to a procedure so that I can:
>>
>> (stuff 'COMPANY)
>>
>> rather than
>>
>> (hash-ref stuff 'COMPANY)
>>
>> Of course, the setup call to exchange the hash for the procedure takes
>> another line, such that I only bother on longer functions with repeated
>> benefit.
>>
>> It certainly would be handy from a succinctness standpoint if a hash acted
>> like a procedure (Any -> Any). Noticing that struct can be a procedure? via
>> a property , I wonder if there's a way for hash? and procedure? to both hold
>> true.
>>
>> It's more than simply saving the 9 letters of hash-ref followed by a space.
>> Performance is not an issue and given a curt enough representation, I'd
>> prefer calling it twice rather than making a local define. My current
>> choices are:
>>
>> ; current STYLE #1
>> (define (current-rpc-receiver data)
>> (define company (hash-ref data 'COMPANY #f))
>> (when company
>> (db-exec ? company))
>>
>> ; current STYLE #2
>> (define (curt-style-rpc-receiver data)
>> (define HF (hash->procedure data))
>> (when (HF 'COMPANY)
>> (db-exec ?. (HF 'COMPANY))
>>
>> ; what would be handier?.
>>
>> (define (handy-style data)
>> (when (data 'COMPANY)
>> (db-exec ? (data 'COMPANY))
>>
>> Thanks in advance for any advice leading to more succinct hash access.
>>
>> ------
>> John Griffin, CTO
>> IT Talent Team, LLC
>> www.ittalentteam.com
>> 855-488-8326
>>
>>
>>
>>
>>
>>
>> ____________________
>> Racket Users list:
>> http://lists.racket-lang.org/users
>
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> ------------------------------
>
> Message: 3
> Date: Mon, 5 Aug 2013 21:27:46 +0530
> From: Vikas Sood <vikaspr...@gmail.com>
> To: users@racket-lang.org
> Subject: [racket] issue with Dr Racket in linux platform.
> Message-ID:
> <capsg1m0ry3guqyagygcgmil8_d-h25jqbm0nhs8-9pjcehn...@mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi
>
> When i am running any program in DR Racket following message is
> being displayed.
>
>
> #%module-begin: illegal use (not a module body) in: (#%module-begin).
>
> I am not able to run even the first sample code in racket in linux.
>
> I am not facing any problem while running the same code in windows.
>
> Kindly provide me with the cause and work around for linux.
>
> regards
>
> Vikas
>
>
> End of users Digest, Vol 96, Issue 10
> *************************************
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