[Haskell-cafe] ByteString.pack behavior

[Dušan Kolář]

Hello all,

  Maybe there is something obvious I can't see, but I have this behavior 
for 6.8.2 ghci:

$ghci ttest1p.hs
GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( ttest1p.hs, interpreted )
Ok, modules loaded: Main.
*Main> encode' [1..100]
Loading package array-0.1.0.0 ... linking ... done.
Loading package bytestring-0.9.0.1 ... linking ... done.
[1,0,2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,0,10,0,11,0,12,0,13,0,... // deleted
*Main> B.pack [0..100]
"\NUL\SOH\STX\ETX\EOT\ENQ\ACK\a\b\t\n\v\f\r\SO\SI\DLE\DC1\DC2\DC3\DC4\NAK\SYN\ETB\CAN\EM\SUB\ESC\FS\GS\RS\US 
!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcd"
*Main> B.pack $ encode' [1..100]
"*** Exception: divide by zero

where ttest1p.hs:

import qualified Data.ByteString as B

encode' [] = []
encode' (x:xs) =
  if x==0 then 0:0:encode' xs
  else (x `mod` 256) : (x `div` 256) : encode' xs


What is the difference, except list length and value structure? Where is 
my error?

Thanks for any hint,

Dusan