[Haskell-cafe] Infinite loop?

2006-02-17 Thread rgo 
Hi all,
my program probably goes into infinite loop... But i cannot understand where 
and why.

code:

import System.Directory

data MyFile = MyDir {
dir_name :: String,
dir_files :: [MyFile]
}
| MyFile {
file_name :: String
}

read_dir_entries :: [FilePath] - IO [MyFile]
read_dir_entries [] = return []
read_dir_entries (name:names) = do
isdir - doesDirectoryExist name;
entry - if isdir
then read_dir name
else return (MyFile {file_name = name});
entries - read_dir_entries names;
return (entry:entries)


read_dir :: FilePath - IO MyFile
read_dir name = do 
content - getDirectoryContents name;
files - read_dir_entries content;
return MyDir {
dir_name = name,
dir_files = files
}

instance Show MyFile where
show (MyDir {dir_name = name, dir_files = files}) = 
\n ++ name ++ :\n ++ show files
show (MyFile {file_name = name}) = \t ++ name ++ \n

main = do
cwd - getCurrentDirectory;
dir - read_dir cwd;
print dir;
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Re: [Haskell-cafe] Infinite loop?

2006-02-17 Thread rgo 
On Fri, 17 Feb 2006 17:19:53 +
Jon Fairbairn [EMAIL PROTECTED] wrote:

 On 2006-02-17 at 20:12GMT rgo wrote:
  Hi all,
  my program probably goes into infinite loop... But i cannot understand 
  where and why.
 
 getDirectoryContents will include . and .., so if you
 follow those, you're bound to loop.
 
 -- 
 Jón Fairbairn  Jon.Fairbairn at cl.cam.ac.uk
 
 

Thanks.
It's the third time in my life when do this error. :-[

here working code:

import System.Directory

data MyFile = MyDir {
dir_name :: FilePath,
dir_files :: [MyFile]
}
| MyFile {
file_name :: FilePath
}

read_dir_entries :: FilePath - [FilePath] - IO [MyFile]
read_dir_entries _ [] = return []
read_dir_entries dirname (name:names) = do
isdir - doesDirectoryExist name;
entry - if (isdir  (name /= .)  (name /= ..))
then read_dir (dirname ++ / ++ name)
else return (MyFile {file_name = name});
entries - read_dir_entries dirname names;
return (entry:entries)

read_dir :: FilePath - IO MyFile
read_dir name = do 
content - getDirectoryContents name;
files - read_dir_entries name content;
return MyDir {
dir_name = name,
dir_files = files
}

instance Show MyFile where
show (MyDir {dir_name = name, dir_files = files}) = 
\n ++ name ++ :\n ++ show files
show (MyFile {file_name = name}) = \t ++ name ++ \n

main = do
cwd - getCurrentDirectory;
dir - read_dir cwd;
print dir;
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