On Thu, 2008-07-10 at 03:16 -0700, Grzegorz Chrupala wrote:
> Hi all,
>
> Is there a less ugly way of avoiding laziness in the code pasted below then
> the use of seq in the last line?
> The program is supposed to split a large input file into chunks and check in
> how many of those chunks each of a list of words appear, as well as the
> total number of chunks. Without the seq it consumes huge amounts of memory.
Strategies! Try
((,) $| rnf) dfs' (n + 1)
Or
(id $| seqPair rnf r0) (dfs', n + 1)
But I don't know if that falls within the intended meaning of `less
ugly'.
jcc
> {-# LANGUAGE BangPatterns, PatternGuards #-}
> import Data.List (foldl')
>
> split delim s
> | [] <- rest = [token]
> | otherwise = token : split delim (tail rest)
> where (token,rest) = span (/=delim) s
>
> main = do
> putStrLn =<< fmap (show . stats ["the","a","and"] . split "<DOC>" . words)
> getContents
>
> stats ws docs = foldl' f ((map (const 0) ws),0) docs
> where f (dfs,n) d = let dfs' = zipWith (\w df -> (df + fromEnum (w
> `elem` d))) ws dfs
> in sum dfs' `seq` (dfs',n+1)
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