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

That worked, though not sure why I had to delete the .o file. On to ghci? Michael --- On Sun, 1/30/11, Paul L wrote: From: Paul L Subject: Re: [Haskell-cafe] Code from Haskell School of Expression hanging. To: "michael rice" Cc: haskell-cafe@haskell.org, "Daniel Fischer" Date: Sunday, January 30, 2011, 7:31 PM 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 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@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@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 wrote: From: Daniel Fischer Subject: Re: [Haskell-cafe] Code from Haskell School of Expression hanging. To: haskell-cafe@haskell.org, "michael rice" 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@localhost ~]$ cd ./SOE/SOE/src

[michael@localhost src]$ ghc --make SimpleGraphics.lhs [2 of 2] Compiling SimpleGraphics   ( SimpleGraphics.lhs, SimpleGraphics.o ) [michael@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@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Regards, Paul Liu