Re: [Haskell-cafe] wxHaskell not in scope

Take a look at the syntax for 'let' inside a 'do'. On Fri, Apr 17, 2009 at 12:57 AM, Tsunkiet Man wrote:

PS: a small note, sorry for multiple mails.

After doing the let ... in function it did not work. =( It gave the error that 'do' has to end with some result. I did:

do let <the function> in <all the code that was behind the do>

and it still didn't work =(. I'm doing something wrong I think.

Thanks for your help.

2009/4/17 Tsunkiet Man

...

Thank you for your response, however if I can't do that, why can the example of wxHaskell do that?

I refer to the following code inside http://darcs.haskell.org/wxhaskell/samples/wx/ (ImageViewer.hs)

Line 99 untill 110

    openImage sw vbitmap mclose status fname       = do -- load the new bitmap            bm <- bitmapCreateFromFile fname  -- can fail with exception            closeImage vbitmap            set vbitmap [value := Just bm]            set mclose [enabled := True]            set status [text := fname]            -- reset the scrollbars            bmsize <- get bm size            set sw [virtualSize := bmsize]            repaint sw        `catch` \err -> repaint sw

if I'm correct the openImage is also defined in the where clause. Therefor by what I think it should not be possible, but it is.

Thanks for everything.

2009/4/17 Lennart Augustsson

...

Variables bound in the do block are not in scope in the where. Use a let inside the do for onOpen instead.

On Thu, Apr 16, 2009 at 11:53 PM, Tsunkiet Man wrote:

...

Hello,

I'm trying to create a GUI by using wxHaskell. However I get the weird error message of "Not in scope "dt"", well so I sorted them so that my so called "dt" was in scope, however it failed. Can someone please tell me how I can solve this error?

           ... A lot of code that is not relevant in my opinion, if I'm wrong please correct me and I will post my full code

            --Debug text --             dt <- staticText f [text := "Hello world!"]

            imagePanel <- panel f [position := Point 2 2, clientSize := Size 100 100, tooltip := "This is a drawPanel", bgcolor := rgb 255 255 255]             set f [ clientSize := Size 700 500,                     menuBar := [mFile, mHelp],                     visible := True,                     on (menu exit) := close f,                     on (menu open) := onOpen f vFile ]

            return ()

            where                 onOpen :: Frame a -> Var b -> IO ()                 onOpen frame var = do   file <- fileOpenDialog frame False True "Open File" [("PGM bestanden (*.pgm)",["*.pgm"]),("Alle bestanden (*.*)",["*.*"])] "" ""                                         case file of                                             Nothing ->      return ()                                             Just file ->    set dt [text := "HELLO"]                                                             return ()

Thank you for your help, I really owe haskell-cafe.

Greetings Tsunkiet Man _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe