This namespace contains replacements for the basic form
elements (input, select, textbox) but with corresponding
states.

The [[select]] item also supports any kind of values for the
`:value` attribute of [[option]]s, not just strings.

Additionally, the new attributes `:invalid` and `:validate` are
supported for all of them, allowing for a declarative way to
use `setCustomValidity` on the dom nodes.

An attribute `:report-validity` can be set to true on input items
and [[form]] to call `reportValidity` on them on every state
change.

Utility to create specialized input fields via parsing of the native value.

(c/isolate-state 0
  (core/input {:type types/integer}))

Input types extend over the `:type` attribute
of [[reacl-c-basics.forms.core/input]] items, giving more control
over the data types of the state value, and to some extend over the
ui controls to enter those values. The type system defined here is
also extensible.

For example, you can ask the user for an integer via

```
(c/isolate-state 0
  (core/input {:type types/integer}))
```

EXPERIMENTAL

Utilities for a more customized display of form validity.

Note: the basic validity of input fields can be defined with the
`:invalid` and `:validate` attribtues
of [[reacl-c-basics.forms.core/input]] etc.

Note: the validation message for native validations (`:pattern`,
`:required` etc) can be modified by using `setCustomValidity` in
`:onInvalid` events depending on the `validity` property.

For visual styling there are the `:required` and `:options` CSS
pseudo-classes, as well as `:valid` and `:invalid`.

For showing validation problems differently than the browser does by
default, use [[with-validity]] and the derived
utils [[form-with-validity]] or [[append-validity]].

To trigger the display of validation problems before submitting a
form, use [[report-validity!]].

See https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Constraint_validation