Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Here's what I came up with.</p> <p>I used the function offered by JB and added two tricks which I learned from the source code of bytestring-lexing (thanks, sclv!). The first one is this function:</p> <pre><code>strict = SB.concat . LB.toChunks</code></pre> <p>It transforms a lazy bytestring into non-lazy one efficiently.</p> <p>The second trick is function <code>Data.ByteString.Internal.inlinePerformIO</code> which is a more efficient variant of unsafePerformIO.</p> <p>Here's complete code that allows a pretty fast number reading:</p> <pre><code> {-# LANGUAGE ForeignFunctionInterface #-} import qualified Data.ByteString.Lazy.Char8 as LB import qualified Data.ByteString as SB import Data.ByteString.Internal (inlinePerformIO) import Foreign.C.String (CString) import Foreign.C (CDouble) import Data.Maybe (fromJust) foreign import ccall unsafe "stdlib.h atof" c_atof :: CString -> IO Double unsafeReadDouble = inlinePerformIO . flip SB.useAsCString c_atof {-# INLINE unsafeReadDouble #-} readDouble = unsafeReadDouble . SB.concat . LB.toChunks readInt = fst . fromJust . LB.readInt </code></pre> <p>And a sample program that calculates the sum of all numbers in the input: <code><pre> main = LB.getContents >>= (print . sum . map readDouble . LB.lines) </code></pre> It processes an 11Mb file (1M numbers) in about 0.5 seconds</p> <p>I also <a href="http://www.haskell.org/haskellwiki/SPOJ#Enormous_Input%3a_Solutions_to_INTEST" rel="nofollow">found</a> <a href="http://www.mail-archive.com/haskell-cafe@haskell.org/msg63973.html" rel="nofollow">several</a> <a href="http://groups.google.com/group/fa.haskell/browse_thread/thread/4133fa71ce97eb0e/fef34d1c3943bbe0#fef34d1c3943bbe0" rel="nofollow">links</a>, where a much more efficient version of <code>readInt</code> is discussed. Presumably one can build a <code>readDouble</code> based on similar ideas. But I think I'll stick with my current version for now.</p>
    singulars
    1. This table or related slice is empty.
    1. POEfficient number reading in Haskell
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USadamax
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload