[Haskell-cafe] Lazy problem ?

[Bulat Ziganshin]

Hello zaxis,

Friday, October 23, 2009, 12:02:57 PM, you wrote:

btw,

good_ssq_red = fmap (statis.str2Ints) $ readFile "ssqHitNum.txt"

or

good_ssq_red = (statis.str2Ints) `fmap` readFile "ssqHitNum.txt"


> good_ssq_red:: IO [Int]
> good_ssq_red =do { 
>     samp <- fmap str2Ints $ readFile "ssqHitNum.txt";
>     return $ statis samp;
> } 
> It works now !  thank you


> Bulat Ziganshin-2 wrote:
>> 
>> Hello zaxis,
>> 
>> Friday, October 23, 2009, 11:15:01 AM, you wrote:
>> 
>>> good_ssq_red = withFile "ssqHitNum.txt" ReadMode (\h -> do {
>>>         samp <- fmap str2Ints $ hGetContents h;
>>>         print samp;    --without this line, the result will always
>>> [1..16]
>>>         return $ statis samp;
>>>     })
>> 
>> withFile and hGetContents shouldn't be used together. both closes file
>> handle and, here, withFile closes it before hGetContents lazily reads
>> data. it's why you need to force reading with print
>> 
>> use readFile instead
>> 
>> 
>> 
>> -- 
>> Best regards,
>>  Bulat                            mailto:Bulat.Ziganshin at gmail.com
>> 
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>> 




-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com