Re: [Haskell-cafe] FPS lib

ForeignPtr requires more memory. Each ForeignPtr has ForeignPtrContents structure attached. In the ForeignPtrContents there is one IORef. Each finalizer adds one Weak# object in the heap. The IORef is a reference to a list of finalizers, so each new finalizer adds a new CONS cell. The finalizers require additional steps in GC time. I haven't tried to measure the difference between ForeignPtr and ByteArray# based implementations but it seems to me that the latter might be better. Of course it will be GHC specific. mmap is valuable only for large string. Typically only when someone wants to read the entire file in the memory. For this case a special data structure might be provided. Cheers, Krasimir