AutoForms

Abstract

AutoForms is a library to ease the creation of Graphical User Interfaces (GUI). It does this by using generic programming to construct GUI components.

The AutoForms user creates an ordinary algebraic data type (ADT), which should reflect the data model of an application. From this ADT AutoForms automatically constructs a GUI component, by using the structure and identifiers of the ADT. To facilitate this construction, AutoForms uses the "Scrap your boilerplate" approach to generic programming.

This component can be displayed using WxHaskell or by an AutoForms custom monad called WxM.. The first facilitates that people who already knows WxHaskell quickly will be able to make GUIs. The second is our attempt at a more type-safe and easier to use GUI toolkit.

Installation

You need the following prerequisites:

• Install WxHaskell. You properly need to use the version in darcs.
• Install Scrap Your Boilerplate.

Download AutoForms release 0.4 and follow the instructions in README.txt.

You can also try the bleeding edge version by doing:

svn export https://autoforms.svn.sourceforge.net/svnroot/autoforms/trunk/AForms

Documentation

The three best sources of documentation is the

• Haddock generated documentation
• The examples in the src/Examples folder in the AutoForms distribution.
• The two examples below
• The AutoForms tutorial

Using AutoForms in cooperation with WxHaskell

The best way to illustrate AutoForms is with some examples.

First, we create a widget consisting of a Double, an Int, and a String. This widget is displayed in a window and the values can be manipulated.

module AFWxExample where

import Graphics.UI.WX
import Graphics.UI.AF.AFWx

main :: IO ()
main = start $
     do w <- frame [text := "AFWx example"]
        p <- panel w []
 
        wid <- makeWidget (0.96::Double, 123::Int, "asdf") p []
        setWidButton <- button p [ text := "Set widget"
                                 , on command := set wid [ value := (0.32, 456, "New Value") ]
                                 ]

        set w [ layout := container p $ fill $ column 10
                           [ widget wid, widget setWidButton ]
              ]

The function makeWidget creates a WxHaskell widget and should be the only thing unrecognisable to an ordinary WxHaskell programmer.

We can also create widgets for custom ADT-s. We will show this be creating a settings dialog for a text editor:

{-# LANGUAGE FlexibleContexts, FlexibleInstances
  , MultiParamTypeClasses, TemplateHaskell, UndecidableInstances #-}

module SettingsForm where

import Graphics.UI.AF.AFWx
import Graphics.UI.WX

data Settings = Settings { lineWrap        :: Bool, splitWords      :: Bool
                         , autoSave        :: Bool, tabulatorStops  :: [Int]
                         , spacesInSteadOfTabulators :: Bool }     deriving (Show, Eq)
$(derive [''Settings])

defaultValues :: Settings
defaultValues = Settings True False False ([4,8,12] ++ [16,20..120]) False

main = start $
      do w <- frame [ text := "Text Editor Settings Forms" ]
         p <- panel w []
         
         wid <- makeWidget defaultValues p []
         
         set p [ layout := widget wid ]

Compared to the previous example there is a few new things. First of all we need to set some compiler options, as shown at the top. Secondly, we need to use the template-Haskell function to derive an instance for the Settings-type. Thirdly, we also need to declare that the Settings-type is an instance of ECCreator.

Using the AutoForms monad (WxM)

The best way to get familiar with the AutoForms monad (WxM) interface to AutoForms is via this tutorial.

Current state and plans

To understand the current state it will be advantageous to know the history of AutoForms. In the beginning this library was inspired by functional forms. E.g. it was an solely an attempt to ease the construction of simple forms (like a preference dialog). Shortly after starting the project, the author discovered that a very similar approach to GUI construction had existed for some time. Namely the clean GEC library. The Clean GEC library do not only try to create forms, but tries to be useable for any kind of GUI. This inspired the author to widen AutoForms scope, by creating functionality for buttons, menus, timers, and more. We encapsulated this functionality in our own monad (WxM). The extra functionality unfortunately delayed the core of AutoForms, namely the automatic transformation of an ADT to a GUI. While this transformation is implemented, it is not as 'inteligent' as it could be.

The larger set of functionality initially proven less than perfect, as it is not as flexible as was initially hoped for. Thus, we have made fundamental changes in this version (0.4). These fundamental changes are not completely finished yet and will be the focus of the next version (0.6).

Users of AutoForms

• Kamiariduki - A system to judge your derivative work's purpose and license is valid with Ceative Commons License Works.

Links

• SourceForge site for AutoForms
• The generic library which is used in this library

Related work

• Compositional Model-Views with Generic Graphical User Interfaces - Library which, like AutoForms, deduce GUI elements from data types.
• FunctionalForms - An approach to making form creation easy. This library is also using WxHaskell. It was the initial inspiration for starting AutoForms.
• Automatic Graphical User Interface Form Generation Using Template Haskell - a paper about using Template Haskell for the automatic construction of GUI forms.

Author of AutoForms

The author of this library is Mads Lindstrøm. Feel free to contact me with questions, ideas, or comments.