Is functional GUI programming possible? [closed]

Answer 1

All these other answers are built up upon functional programming, but make a lot of their own design decisions. One library that is built basically entirely out of functions and simple abstract data types is gloss. Here is the type for its play function from the source

-- | Play a game in a window. Like `simulate`, but you manage your own input events.
play    :: Display              -- ^ Display mode.
        -> Color                -- ^ Background color.
        -> Int                  -- ^ Number of simulation steps to take for each second of real time.
        -> world                -- ^ The initial world.
        -> (world -> Picture)   -- ^ A function to convert the world a picture.
        -> (Event -> world -> world)    
                -- ^ A function to handle input events.
        -> (Float -> world -> world)
                -- ^ A function to step the world one iteration.
                --   It is passed the period of time (in seconds) needing to be advanced.
        -> IO ()

As you can see, it works entirely by supplying pure functions with simple abstract types, that other libraries help you with.

Answer 2

To address this I posted some thoughts of mine in using F#,

http://fadsworld.wordpress.com/2011/04/13/f-in-the-enterprise-i/ http://fadsworld.wordpress.com/2011/04/17/fin-the-enterprise-ii-2/

I'm also planning to do a video tutorial to finish up the series and show how F# can contribute in UX programming.

I'm only talking in context of F# here.

-Fahad

Answer 3

My question is, is it possible to have a functional approach to GUI programming?

The key words you are looking for are "functional reactive programming" (FRP).

Conal Elliott and some others have made a bit of a cottage industry out of trying to find the right abstraction for FRP. There are several implementations of FRP concepts in Haskell.

You might consider starting with Conal's most recent "Push-Pull Functional Reactive Programming" paper, but there are several other (older) implementations, some linked from the haskell.org site. Conal has a knack for covering the entire domain, and his paper can be read without reference to what came before.

To get a feel for how this approach can be used for GUI development, you might want to look at Fudgets, which while it is getting a bit long in the tooth these days, being designed in the mid 90s, does present a solid FRP approach to GUI design.