Formlets
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Formlets are a way to build composable HTML forms that are type-safe, handle errors, are abstract, and easy to combine into larger forms. The key feature of formlets is that they are composable, like integers that can be added together or enumerables that can be selected, filtered and ordered. This allows text boxes, text areas, dropdowns and other form elements to be combined to create complex nested composite forms through binding operations. Demo code shows how common form validation and error handling tasks can be abstracted using formlets.
![Formlets are a way of building
[HTML] forms that are type-safe,
handle errors, abstract and are easy to
combine into bigger forms
Haskell Wiki](https://image.slidesharecdn.com/formlets-160529185122/85/Formlets-21-320.jpg)
![function notEmpty(lbl: string): IFormlet<string> {
return enhanceWithLabel(lbl, enhanceWithErrorVisualizer(
ensureNotEmpty(input(""))))
}
function createAddress(vs: string[]): IAddress;
function address(lbl: string): IFormlet<IAddress> {
return enhanceWithGroup(lbl, map(createAddress, many(
[
notEmpty("Street"),
notEmpty("Zip"),
notEmpty("City"),
notEmpty("State")
])))
}
let invoiceAddress = address("Invoice Address")](https://image.slidesharecdn.com/formlets-160529185122/85/Formlets-24-320.jpg)
Formlets
- 1. FORMLETS A better way to create forms?
- 2. FORMS Forms are used to accept input from the user Forms benefit from structure and predictability Forms should provide feedback to the user on the data quality (validation) Once sufficient quality is reached the user submits the data Some applications may have 100+ different forms
- 8. Design Patterns to the rescue?
- 17. Formlet<string * string> TextBox * TextBox string * string
- 18. FORMLETS We need some kind of flexible way to bind two Formlets into a new Formlet As the result of the binding operation is a Formlet the result can be bound as well This gives endless composability Like integers are composable: 1 + 2 + 3 + 4 Like IEnumerables are composable: l.Select (...).Where (...).OrderBy () Our Formlets are composable: TextBox + TextBox + TextBox + TextBox
- 19. Demo
- 21. Formlets are a way of building [HTML] forms that are type-safe, handle errors, abstract and are easy to combine into bigger forms Haskell Wiki
- 22. The key feature of formlets is that they are composable Formaggio
- 24. function notEmpty(lbl: string): IFormlet<string> { return enhanceWithLabel(lbl, enhanceWithErrorVisualizer( ensureNotEmpty(input("")))) } function createAddress(vs: string[]): IAddress; function address(lbl: string): IFormlet<IAddress> { return enhanceWithGroup(lbl, map(createAddress, many( [ notEmpty("Street"), notEmpty("Zip"), notEmpty("City"), notEmpty("State") ]))) } let invoiceAddress = address("Invoice Address")
- 25. LINKS WebSharper Formlets http://websharper.com/docs/formlets WebSharper Piglets http://websharper.com/docs/piglets WPF Formlet gist https://gist.github.com/mrange/f5fbc34da14b34d4064f536de60e026b Great Scott! http://www.slideshare.net/ScottWlaschin/railway-oriented-programming http://www.slideshare.net/ScottWlaschin/fp-patterns-ndc-london2014 The essence of Form Abstraction (Wadler obviously) http://homepages.inf.ed.ac.uk/wadler/papers/formlets-aplas/formlets-aplas.pdf
- 26. Questions?