小编com*_*ose的帖子

我想使用Haskell计算存储在文件中的唯一块.该块只是连续的字节,长度为512,目标文件的大小至少为1GB.

这是我最初的尝试.

import           Control.Monad
import qualified Data.ByteString.Lazy as LB
import           Data.Foldable
import           Data.HashMap
import           Data.Int
import qualified Data.List            as DL
import           System.Environment

type DummyDedupe = Map LB.ByteString Int64

toBlocks :: Int64 -> LB.ByteString -> [LB.ByteString]
toBlocks n bs | LB.null bs = []
              | otherwise = let (block, rest) = LB.splitAt n bs
                            in block : toBlocks n rest

dedupeBlocks :: [LB.ByteString] -> DummyDedupe -> DummyDedupe
dedupeBlocks = flip $ DL.foldl' (\acc block -> insertWith (+) block 1 $! acc) …

我对C++ unordered_map(aka hash_map)容器及其包装库进行了FFI绑定libstl.a.它第一次运作良好.但在某些时候,它无法将库与以下错误消息链接,我无法弄清楚原因.

$ ghci -L. -lstl -lstdc++ 
GHCi, version 7.6.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading object (static archive) ./libstl.a ... done
Loading object (dynamic) /usr/lib/gcc/x86_64-linux-gnu/4.7/libstdc++.so ... done
final link ... ghc: ./libstl.a: unknown symbol `_ZZNKSt8__detail20_Prime_rehash_policy11_M_next_bktEmE10__fast_bkt'
linking extra libraries/objects failed

该库的源代码位于https://github.com/comatose/stl-container.任何帮助将不胜感激.