[Haskell-cafe] Code from Haskell School of Expression hanging.

[Paul L]

Maybe you want to remove Snowflake.o (or even *.o) and then try compiling it
again.

Regards,
Paul Liu

On Sun, Jan 30, 2011 at 4:11 PM, michael rice <nowgate at yahoo.com> wrote:

> SimpleGraphics has a bunch of main programs: main0, main1, main2, main3,
> and main3book. I sequentially changed each to main and ran all five
> successfully.
>
> Then I did the same for Snowflake.lhs (see code below) which already had a
> single main function.
>
> Michael
>
> ==============
>
> [michael at localhost src]$ ghc --make Snowflake -main-is Snowflake
> Linking Snowflake ...
> /usr/lib/ghc-6.12.3/libHSrtsmain.a(Main.o): In function `main':
> (.text+0x10): undefined reference to `ZCMain_main_closure'
> /usr/lib/ghc-6.12.3/libHSrtsmain.a(Main.o): In function `main':
> (.text+0x18): undefined reference to `__stginit_ZCMain'
> collect2: ld returned 1 exit status
> [michael at localhost src]$
>
> ==============
>
>
> This code was automatically extracted from a .lhs file that
> uses the following convention:
>
> -- lines beginning with ">" are executable
> -- lines beginning with "<" are in the text,
>      but not necessarily executable
> -- lines beginning with "|" are also in the text,
>      but are often just expressions or code fragments.
>
> > module Snowflake where
> > import SOE
>
> > m = 81  :: Int -- multiple of 3 for triangle size
> > x = 250 :: Int -- x and y coordinates of
> > y = 250 :: Int --         center of snowflake
> > colors = [ Magenta, Blue, Green, Red, Yellow ]
>
> > snowflake :: Window -> IO ()
> > snowflake w = do
> >   drawTri w x y m 0 False -- draw first triangle w/flat top
> >   flake   w x y m 0 True  -- begin recursion to complete job
>
> > flake :: Window -> Int -> Int -> Int -> Int -> Bool -> IO ()
> > flake w x y m c o = do
> >   drawTri w x y m c o  -- draw second triangle
> >   let c1 = (c+1)`mod`5 -- get next color
> >   if (m<=3) then return ()  -- if too small, we're done
> >      else do
> >        flake w (x-2*m) (y-m) (m`div`3) c1 True  -- NW
> >        flake w (x+2*m) (y-m) (m`div`3) c1 True  -- NE
> >        flake w  x    (y+2*m) (m`div`3) c1 True  -- S
> >        flake w (x-2*m) (y+m) (m`div`3) c1 False -- SW
> >        flake w (x+2*m) (y+m) (m`div`3) c1 False -- SE
> >        flake w  x    (y-2*m) (m`div`3) c1 False -- N
>
> > drawTri :: Window -> Int -> Int -> Int -> Int -> Bool -> IO ()
> > drawTri w x y m c o =
> >   let d =  (3*m) `div` 2
> >       ps = if o
> >            then [(x,y-3*m),  (x-3*m,y+d), (x+3*m,y+d)] -- side at bottom
> >            else [ (x,y+3*m), (x-3*m,y-d), (x+3*m,y-d)] -- side at top
> >   in drawInWindow w
> >        (withColor (colors !! c)
> >           (polygon ps))
>
> > main
> >   = runGraphics (
> >     do w <- openWindow "Snowflake Fractal" (500,500)
> >        drawInWindow w (withColor White
> >          (polygon [(0,0),(499,0),(499,499),(0,499)]))
> >        snowflake w
> >        spaceClose w
> >     )
>
> > spaceClose :: Window -> IO ()
> > spaceClose w
> >   = do k <- getKey w
> >        if k==' ' || k == '\x0'
> >           then closeWindow w
> >           else spaceClose w
>
>
> --- On *Sun, 1/30/11, Daniel Fischer <daniel.is.fischer at googlemail.com>*wrote:
>
>
> From: Daniel Fischer <daniel.is.fischer at googlemail.com>
> Subject: Re: [Haskell-cafe] Code from Haskell School of Expression hanging.
> To: haskell-cafe at haskell.org, "michael rice" <nowgate at yahoo.com>
> Date: Sunday, January 30, 2011, 6:48 PM
>
>
> On Monday 31 January 2011 00:27:41, michael rice wrote:
> > And here's the same with GHC. It never gets to linking and creating an
> > executable the way the GLFW sample program does.
> >
> > Michael
> >
> > ===============
> >
> > [michael at localhost ~]$ cd ./SOE/SOE/src
> > [michael at localhost src]$ ghc --make SimpleGraphics.lhs
> > [2 of 2] Compiling SimpleGraphics   ( SimpleGraphics.lhs,
> > SimpleGraphics.o ) [michael at localhost src]$
>
> The module name is not Main, so to get an executable, you have to tell ghc
> what the Main module is.
> Assuming SimpleGraphics.lhs contains a main function,
>
> $ ghc --make SimpleGraphics -main-is SimpleGraphics
>
> should do it.
>
> Cheers,
> Daniel
>
>
>
>
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>
>


-- 
Regards,
Paul Liu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20110130/83adce7e/attachment.htm>