sending Int32, Int64 seems broken

[jwaldmann]

When I replace Int by Data.Int.Int32 or Data.Int.Int64, I get out-of-memory at runtime:

http://dfa.imn.htwk-leipzig.de/cgi-bin/gitweb.cgi?p=skpp-ws12.git;a=tree;f=cloud;h=be068913876db478e721cecf80947f451b63c354;hb=b3f8ba674bde08da7d2db7b477e0b7b55f13b560

Bitcount: Bitcount: Bitcount: Bitcount: out of memory (requested 1048576 bytes)out of memory (requested 1048576 bytes)
out of memory (requested 1048576 bytes)

out of memory (requested 1048576 bytes)

[hyperthunk]

What does the Binary instance for Data.Int.Int32 look like?

[jwaldmann]

binary-0.5.1.1 (comes with ghc-7.6.1)

-- Int64s are written as a 4 bytes in big endian format
instance Binary Int64 where
    put i   = put (fromIntegral i :: Word64)
    get     = liftM fromIntegral (get :: Get Word64)

seems to work in ghci

Prelude> import Data.Binary
Prelude Data.Binary> import Data.Int
Prelude Data.Binary Data.Int> decode ( encode (42 :: Int64) ) :: Int64
Loading package array-0.4.0.1 ... linking ... done.
Loading package deepseq-1.3.0.1 ... linking ... done.
Loading package bytestring-0.10.0.0 ... linking ... done.
Loading package containers-0.5.0.0 ... linking ... done.
Loading package binary-0.5.1.1 ... linking ... done.
42

[hyperthunk]

Not sure about this, but certainly looks like a bug => updating label.

[jwaldmann]

OK, this is weird, but it is not the fault of C.D.P. I distilled this from my example program:

import Data.Int
import System.Environment

bitcount x = if x > 0 
    then let (d,m) = divMod x 2 in  bitcount d + m
    else 0

main = do
    [ arg ]  <- getArgs
    print $ sum  $ map bitcount
          [ 0 :: Int64 .. 2^read arg - 1 ]

this gives me Stack Overflow for arguments 18 ..24, and Out of memory for 25.

I guess some loop unrolling/fusion is not happening for Int64 (but it is, for Int).

[hyperthunk]

Thanks for boiling it down and confirming it's not a CH issue - much appreciated.