Hi, A "Checkbox" is instance of the class Checkable: http://wxhaskell.sourceforge.net/doc/ Graphics.UI.WX.Classes.html#t%3ACheckable This means you can "get" and "set" the "checked" property for checkboxes. for example: c <- get cbEdit checked set cbEdit [checked := not c ] The following code makes the checkbox print its state every time it is checked or unchecked: cbEdit <- checkBox f [text := "Edit Mode" ] set cbEdit [ on command := do v <- get cbEdit checked print v ] Arthur PS: there is a mailinglist for wxhaskell-related questions: http://lists.sourceforge.net/lists/listinfo/wxhaskell-users On 14-sep-05, at 17:15, Mark Carter wrote:

I'm a complete n00b to Haskell, and I am trying to write an experimental app using wxHaskell. I'm getting on suprisingly well, given that I have practially no idea what I'm doing.

In my main loop I have cbEdit <- checkBox p1 [text := "Edit Mode", on command := onCbEdit textlog ] where p1 is a panel, and textlog is a textCtrl that I want to write output to. In my where clause I have defined:

onCbEdit textlog = do appendText textlog "onCbEdit\n"

So far, this works. The thing that's got me totally stumped is this: suppose I want onCbEdit to do something dependent on the state of the checkbox (i.e. whether it is checked or unchecked). I've tried a variety of things, but I can't get anything to work.

To put things into a wider context, here's the message I posted to fa.haskell yesterday:

I'm the rawest of n00bs to Haskell. I was interested in evaluating it, and I've seen some GUI stuff that looked pretty impressive.

I wanted to write a protoype for a commercial application to do hydrocarbon accounting. Which is to say, you've a number of so-called "streams" - think of them as graph nodes - feeding into each other in a directed fashion (assume the graph is acyclic). Then there's a bunch of business logic which determines how the values of one stream are affected by the values in another. An example of a stream might be a platform. Another one might be a well. Each stream would display on the window as some funky symbol, with its name underneath.

It would be nice if the application had an edit mode, where you could add, move, delete, and join streams in a window; and a data mode, where you could click on the stream you were interested in and examine its properties.

Is there a Haskell GUI toolkit which is particularly suitable for this?

Other requirements of the toolkit would be: * Works on Windows (XP) * commercial-friendly licence: GPL is out, and even LGPL is a bit fiddly * free * bonus points for being easy to use, and well-documented

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