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(Object layering)
Line 25: Line 25:
 
textBox-text -< "test"
 
textBox-text -< "test"
 
filename <- newVar Nothing
 
filename <- newVar Nothing
notify filename hatCover
+
addNotify filename hatCover
 
lbl-text =< with filename $ \x ->
 
lbl-text =< with filename $ \x ->
 
case x of
 
case x of

Revision as of 00:30, 18 July 2006

A design for a GUI library which is more like Haskell and less like C.

Link: http://www.cse.unsw.edu.au/~chak/haskell/ports/

1 Thoughts by

Neil Mitchell

2 The Var concept

This is the low level stuff, on which the library will be built

data Var a = ...
data Notify
get :: Var a -> IO a
set :: Var a -> a -> IO ()
addNotify :: Var a -> IO () -> IO Notify
remNotify :: Notify -> IO ()
newVar :: a -> IO (Var a)

3 Object layering

textBox-text -< "test"
filename <- newVar Nothing
addNotify filename hatCover
lbl-text =< with filename $ \x ->
                 case x of
                     Nothing -> "Select a file"
                     Just x -> "Loaded: " ++ x


where

(-) :: GtkObject -> GtkProp -> Var a -- ignoring lots of details here
(-<) :: Var a -> a -> IO ()
(=<) :: Var a -> Action a -> IO ()
with :: Var a -> (a -> b) -> Action b