[racket-users] Re: [racket] Sorry, but what's the correct way to use `#lang scribble/lp2`

[WarGrey Gyoudmon Ju]

Oh, yes, perhaps I did not understand Symbols well, especially in TEXT MODE.
I don't remember how did I find the solution.

Nonetheless, thank you all the same.

On Tue, Jan 12, 2016 at 2:42 AM, Ismael Figueroa 
wrote:

> Maybe it is too late for this, but I run into the same issue just now...
>
> In my case I get the same error when using:
>
> @include-section["path.rkt"]
>
> but it works when using
>
> @include-section[(submod "path.rkt" doc)]
>
> probably because the scribble/lp2 is not providing the doc submodule
> expected by scribble itself...
>
> Cheers
>
>
>
> 2015-02-21 11:22 GMT-02:00 WarGrey Gyoudmon Ju :
>
>> Glad to see the literate programming technology updated.
>> I thought it might be a "Forgotten Feature" since the rest of scribble is
>> so powerful and I cannot find any code base use it.
>> Thank you.
>>
>> So... there still should be more examples to work with it.
>> What's the extra work (rather than simply replacing scribble/lp with
>> scribble/lp2) has to be done to make it able to be `include-section`ed?
>>
>> `scribble path.rkt`
>> `raco scribble path.rkt`
>> `(include-section (submod "path.rkt" doc))`
>> All of these complain:
>> path-only: contract violation
>>   expected: (or/c path-string? path-for-some-system?)
>>   given: #f
>>
>> and `(include-section "path.rkt")` complains:
>> handbook.scrbl:71:18: only-in: identifier `doc' not included in nested
>> require spec at: "path.rkt" in: (only-in "makefile.rkt" (doc doc))
>>
>>
>> 
>>   Racket Users list:
>>   http://lists.racket-lang.org/users
>>
>>
>
>
> --
> Ismael
>

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Re: [racket-users] Web server: can't get radio-group formlet to process

[Jay McCarthy]

Hi Marc,

Most formlets are typed as `(formlet/c (or/c false/c binding?))` where
the `binding?` is returned when the thing is there and the `#f` is
returned when it isn't. However, if you use `required`, then an
exception is thrown on the `#f` because the form element must be
present. Formlets like `input-string` include a call to `required`. I
think that you either want to handle the `#f` or use `default` to have
a default value present. Similarly most formlets like `text-input`
have an optional `#:value` keyword for starting them off with a value.

I think a better form DSL could be built out of formlets that
automatically did client & server-side checking with looping
re-submission until correct, etc. But that's not what formlets are yet
and you have to roll it yourself.

Jay


On Sun, Jan 10, 2016 at 9:05 PM, Marc Kaufmann
 wrote:
> Thanks.
>
> Another question about formlets: when I use (formlet-process formlet-name)
> it will often raise errors when a field doesn't have a value. Is there an
> easy way of capturing errors, in particular to show the form as it was
> entered by the user, but with an error message at the top, rather than
> blowing up?
>
> One way I can imagine doing this is to catch the errors via (with-handlers
> ... ), and then resend the form with previous answers pre-populated. So, I
> would do the following, where 'answer' is the string ("Yes" or "No") that
> was associated with the checked answer previously.
>
> (define (rg-formlet answer)
>   (define (was-answer? a)
> (equal? a answer))
>   (formlet
> (label
>   ,{(radio-group '("Yes" "No") #:checked was-answer?) . => . answer})
> answer))
>
> Is this the way to do it, or is there an easier way (since forms with
> missing elements can't be such a rarity - and yes, I'll do checking on the
> client-side as well).
>
> Thanks,
> Marc
>
> On Sun, Jan 10, 2016 at 5:08 PM, Jay McCarthy 
> wrote:
>>
>> On Sun, Jan 10, 2016 at 3:50 PM, Marc Kaufmann
>>  wrote:
>> > Hi,
>> >
>> > I manage to get the basic formlets to work, and tried the radiogroup,
>> > but it
>> > fails with the following error: "input-group: invalid selection #f",
>> > even
>> > though I had it selected. After some playing around, I saw that there
>> > are
>> > two input_0 fields being sent on submit, since I have another formlet on
>> > the
>> > same page (with a separate formlet-display and formlet-process).
>> >
>> > My question is: If I use formlets, do I have to put all the formlets
>> > into
>> > one big formlet on every page, as otherwise fields will have the same
>> > name
>> > attribute, and there will be clashes?
>>
>> Each form can have only one formlet. There can be different forms on a
>> page, I believe.
>>
>> Jay
>>
>> > Thanks,
>> > Marc
>> >
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> > Groups
>> > "Racket Users" group.
>> > To unsubscribe from this group and stop receiving emails from it, send
>> > an
>> > email to racket-users+unsubscr...@googlegroups.com.
>> > For more options, visit https://groups.google.com/d/optout.
>>
>>
>>
>> --
>> Jay McCarthy
>> Associate Professor
>> PLT @ CS @ UMass Lowell
>> http://jeapostrophe.github.io
>>
>>"Wherefore, be not weary in well-doing,
>>   for ye are laying the foundation of a great work.
>> And out of small things proceedeth that which is great."
>>   - D 64:33
>
>



-- 
Jay McCarthy
Associate Professor
PLT @ CS @ UMass Lowell
http://jeapostrophe.github.io

   "Wherefore, be not weary in well-doing,
  for ye are laying the foundation of a great work.
And out of small things proceedeth that which is great."
  - D 64:33

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[racket-users] Re: [racket] Sorry, but what's the correct way to use `#lang scribble/lp2`

[Ismael Figueroa]

Maybe it is too late for this, but I run into the same issue just now...

In my case I get the same error when using:

@include-section["path.rkt"]

but it works when using

@include-section[(submod "path.rkt" doc)]

probably because the scribble/lp2 is not providing the doc submodule
expected by scribble itself...

Cheers



2015-02-21 11:22 GMT-02:00 WarGrey Gyoudmon Ju :

> Glad to see the literate programming technology updated.
> I thought it might be a "Forgotten Feature" since the rest of scribble is
> so powerful and I cannot find any code base use it.
> Thank you.
>
> So... there still should be more examples to work with it.
> What's the extra work (rather than simply replacing scribble/lp with
> scribble/lp2) has to be done to make it able to be `include-section`ed?
>
> `scribble path.rkt`
> `raco scribble path.rkt`
> `(include-section (submod "path.rkt" doc))`
> All of these complain:
> path-only: contract violation
>   expected: (or/c path-string? path-for-some-system?)
>   given: #f
>
> and `(include-section "path.rkt")` complains:
> handbook.scrbl:71:18: only-in: identifier `doc' not included in nested
> require spec at: "path.rkt" in: (only-in "makefile.rkt" (doc doc))
>
>
> 
>   Racket Users list:
>   http://lists.racket-lang.org/users
>
>


-- 
Ismael

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[racket-users] Re: Code critique request: data/fetch, proc for walking hashes/lists

[Jack Firth]

I'd probably prefer using a fold over explicit recursion. This gets easier if 
you split your code into two steps - one that does just one level of lookup, 
and one that does nested lookups. Additionally, I'd prefer list indexes rather 
than pair lookup functions:

(define (data/ref s key)
  (cond
[(hash? s) (hash-ref s key)]
[(list? s) (list-ref s key)]
[else fail-somehow ...]))

(define (data/fetch s keys)
  (define (fetch-once key s)
(data/ref s key))
  (foldl fetch-once s keys))


> (data/ref (hash 'a 1 'b 2) 'a)
1
> (data/ref '(a b c) 2)
'c
> (data/fetch (hash 'a '(foo bar baz) 'b 0) '(a 2))
'baz

By splitting the recursion (define (data/ref s key)
  (cond
[(hash? s) (hash-ref s key)]
[(list? s) (list-ref s key)]
[else fail-somehow ...]))

(define (data/fetch s keys)
  (define (fetch-once key s)
(data/ref s key))
  (foldl fetch-once s keys))


> (data/ref (hash 'a 1 'b 2) 'a)
1
> (data/ref '(a b c) 2)
'c
> (data/fetch (hash 'a '(foo bar baz) 'b 0) '(a 2))
'baz

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[racket-users] Re: Code critique request: data/fetch, proc for walking hashes/lists

[Jack Firth]

I'd probably prefer using a fold over explicit recursion. This gets easier if 
you split your code into two steps - one that does just one level of lookup, 
and one that does nested lookups. Additionally, I'd prefer list indexes rather 
than pair lookup functions:

(define (data/ref s key)
  (cond
[(hash? s) (hash-ref s key)]
[(list? s) (list-ref s key)]
[else fail-somehow ...]))

(define (data/fetch s keys)
  (define (fetch-once key s)
(data/ref s key))
  (foldl fetch-once s keys))


> (data/ref (hash 'a 1 'b 2) 'a)
1
> (data/ref '(a b c) 2)
'c
> (data/fetch (hash 'a '(foo bar baz) 'b 0) '(a 2))
'baz

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