On Friday 07 October 2005 16:51, Joel Reymont wrote:
It seems that (BigEndian x) <- peek ptr_x is the culprit.
On Oct 7, 2005, at 4:48 PM, Joel Reymont wrote:
This code hangs for me for whatever reason when I run it at the ghci prompt. It does not matter whether I load it from a file or type it in.
This is because I got the peek vs. peekByteOff semantics completely wrong. Sorry for that. (peekByteOff i) does exactly the same as peek, only with a pointer that is advanced (i) bytes forward. That means, the code I sent reads and writes to random memory locations; no wonder the program hangs (I am astonished it doesn't crash). In order to define byte swapping instances of Storable, you have to swap the bytes /in memory/ and afterwards interprete them as whatever value they were originally. This is like C programming in Haskell, which is possible, but no less ugly than the C version. Cheers, Ben