hi all,
two things:
1/ i do something and i'd like to know if it is correct
2/ i propose something about 1/
1/ i want to read some binary file (e.g. targa file format : *.tga).
i do this :
-- first way : via IOUArray
showInfoHeader1 handle = do
a <- newArray_ (1,8) :: IO (IOUArray Int Word8)
hGetArray handle a 8
idLength <- readArray a 1 -- or getElems...
putStrLn ("id length : " ++ show idLength)
return ()
-- second way : via c-like array
showInfoHeader2 handle = do
b <- mallocArray 8 :: IO (Ptr Word8)
hGetBuf handle b 8
[idLength] <- peekArray 1 b -- or peakArray 8 b
putStrLn ("id length : " ++ show idLength)
free b
return ()
so, briefly, i have to read some content into some kind of buffer
(IOUArray Int Word8 or Ptr Word8), then get one (or more) elements
from the buffor into a standard haskell variable (is it the correct
word ?) (or list).
in the second case, i also have to free the buffer.
in some case, when the data is more than one Word8 long, i have to
'reconstruct' it, i.e.:
[x1,x2] <- getElems a
let x = fromIntegral x1 + fromIntegral x2 * 256 :: Int
is it the correct way to read binary files ?
-------
2/ haskell is (i heard that once ... :-) a high level language, so it
has (must have) good support for abstraction...
but in 1/, i have to choose between different kind of array
representation (and i dont know which one is better) and it seems to
me that the resulting code (compiled) would have to be the same.
the thing i want to say here is : what i want to do is pretty obvious
(in both code) but could be expressed more succintly and with only one
possible syntax:
for example, the couples (hGet*,peek/readArray) could be written in one line;
also, one line for the reading/reconstructing more-than-one-Word8 value.
is it already possible ?
would it be interesting to add such capabilities to haskell ? (i think so)
i can try to add it but i need some pointers about how to do it.
thx a lot,
vo minh thu
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