Re: [Haskell-cafe] dynamic web form generation for algebraic data types

2 Mar 2023

      ...
So I should re-phrase my question:
Has anyone extended tangible values to Generic types and given them a
modern html interface?
I think the answer is "no"; and it would be extremely great if someone did.

But I think at least part of the problem is that one is forced to marry
oneself to a particular web framework/JavaScript library, and is therefore
immediately out of date :(

Personally, back in the day I quite like the API put out by Yesod for
auto-generating forms - https://www.yesodweb.com/book/forms - but I don't
think it quite does what you want. Maybe it's a simple adaptation, though
(of course, forcing yourself to use a particular flavour of
javascript/styling approach).

On Thu, 2 Mar 2023 at 16:41, Olaf Klinke  wrote:
...
On Thu, 2023-03-02 at 07:34 -0800, Ivan Perez wrote:
...
All of this reminds me of Conal Elliott's Tangible Values.
http://conal.net/papers/Eros/
(Not for web but the idea still applies.)
Ivan
Yes, the concept has been re-invented multiple times, as is the case
with most good ideas. TVs are general enough to bolt a web interface on
top, I guess.
Seems that Conal, too, has not solved the sum type problem.
The tangible value GADT
https://hackage.haskell.org/package/TV-0.5.0/docs/Interface-TV-Input.html
has a Pair constructor but not for Sum. I wonder whether there is a
deeper categorical reason for this.
So I should re-phrase my question:
Has anyone extended tangible values to Generic types and given them a
modern html interface?
Olaf
...
On Thu, 2 Mar 2023 at 07:02, Olaf Klinke  wrote:
...
On Thu, 2023-03-02 at 15:51 +0200, Georgi Lyubenov wrote:
...
Hey Olaf,
This is not an answer to your question, but I was reminded of
...
...
...
which is a language
with a "browser"[1] that allows you to type in terms and get back
webpages based on those terms
"automagically", which sounds like exactly what you need. I don't
know
how it's implemented, so I don't know if
it is actually relevant to you, but it is worth noting that Grace
itself
is implemented in Haskell.
Cheers,
Georgi
[0] https://github.com/Gabriella439/grace
[1] https://trygrace.dev/
On 3/2/23 12:54, Olaf Klinke wrote:
...
Dear Cafe,
has anyone ever attempted (and maybe succeeded) in building dynamic
forms using one of the Haskell web frameworks (Yesod,Servant,...)?
By "dynamic" form I mean a form that changes the number of fields
...
...
...
...
on selections the user makes in other fields of the form.
For example, say one has an algebraic data type
data T = Number Int | Check Bool T
A form for such a type would initially consist of radio buttons or
a
drop-down list with options "Number" and "Check" that lets the user
select the constructor. When "Number" is selected, an <input
type="number"> field is shown. When "Check" is selected, an <input
type="checkbox"> is displayed next to another form of this kind.
In the end, one would use the GHC.Generics machinery to generate
...
...
...
...
for a wide range of algebraic data types. I've seen this in the
Clean
language's iTask library [1] and it's very convenient.
Of course this would involve a lot of JavaScript like
document.createElement() as well as book-keeping how to re-asseble
Grace[0],
based
forms
the
...
...
...
...
fields into a T value upon submission. At least the latter is
already
handled by libraries such as yesod-form.
Olaf
[1] https://cloogle.org/src/#itasks/iTasks/UI/Editor/Generic
[2] https://github.com/haskell-servant/servant-swagger/issues/80
Thanks for the pointer!
The Grace README says under Notable Omissions:
...
Recursion or recursive data types
Grace only supports two built-in recursive types, which are List and
JSON, but does not support user-defined recursion or anonymous
recursion.
User-defined datatypes
All data types in Grace are anonymous (e.g. anonymous records and
anonymous unions), and there is no concept of a data declaration
The tutorial shows how Grace function inputs are mapped to forms, where
functions with List input indeed have a form that is "dynamic" in the
sense I defined. Otherwise there is only one input field per function
argument. That means complex types are to be input in JSON syntax and
parsed.
Instead of a DSL, I'd prefer a shallow embedding into Haskell, so that
one can leverage all the available machinery.
Yet Grace already goes a long way towards what I am after.
Olaf
_______________________________________________
Haskell-Cafe mailing list
To (un)subscribe, modify options or view archives go to:
http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Only members subscribed via the mailman list are allowed to post.
_______________________________________________
Haskell-Cafe mailing list
To (un)subscribe, modify options or view archives go to:
http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Only members subscribed via the mailman list are allowed to post.
-- 
Noon van der Silk, ن

http://silky.github.io/

"My programming language is kindness."