nano-ui-form

Forms for nano-ui, built on ditto.

A form is an applicative value. Each input draws a nano-ui widget and parses its value; validators attach errors that appear under the field.

{-# LANGUAGE OverloadedStrings #-}

import Data.Text (Text)
import NanoUI (NanoUI, label)
import NanoUI.Form hiding (label)

data Signup = Signup Text Text

signup :: Form Text Signup
signup =
  Signup
    <$> withFieldErrors (inputText "Name" "" `prove` notEmpty "Name is required")
    <*> withFieldErrors (inputText "Email" "" `prove` validEmail (const "Not an email address"))

view :: NanoUI ()
view = do
  submitted <- nanoFormSubmit "signup" "Sign up" signup
  case submitted of
    Just (Signup name _) -> label ("Welcome, " <> name)
    Nothing -> pure ()

nanoFormSubmit adds a submit button and yields the value on the frame the form is submitted. nanoFormLive yields the value whenever the form is valid, nanoFormEx takes a FormConfig, and runNanoForm returns the form's view and result separately.

Running

cabal run nano-ui-form-example -f sdl

The example needs nano-ui-sdl, behind this package's sdl flag (off by default, and on in this repository's cabal.project). The library itself does not depend on a backend.