On Fri, Nov 14, 2014 at 05:47:16PM +0100, Wojtek Narczyński wrote:
On 14.11.2014 10:43, zhangjun.julian wrote:
emptyMap = DM.empty::(DM.Map (String,String) Int)
Laziness makes your data swell.
1) Try using ByteString or Text instead of String. 2) Try the UNPACK pragma, AFAIR it requires -O2. data Key = Key {-# UNPACK #-} !ByteString {-# UNPACK #-} !ByteString https://hackage.haskell.org/package/ghc-datasize - this package will help you to determine the actual data size
This is certainly true, but there is a distinction to be drawn between "swollen data" that is a few times bigger than it could be, and a space leak. Zhangjun Julian's biggest problem is definitely the latter. There's no reason that compiling a dictionary counting occurences and printing it out should consume 9GB. Once the space leak is fixed your suggestions will help reduce memory usage further. Tom