On 2007-11-08, David Roundy <[EMAIL PROTECTED]> wrote: > On Wed, Nov 07, 2007 at 10:10:16PM +0000, Jules Bean wrote: >> Joel Reymont wrote: >> >Is there such a thing as memory-mapped arrays in GHC? >> >> In principle, there could be an IArray instance to memory-mapped files. >> >> (There could also be a mutable version, but just the IArray version >> would be useful). > > The IArray instance would be unsafe, however, because the contents of the > file could change after you opened it, breaking referential transparency.
Or even crashing, if the size becomes smaller than the mapped area. > I don't know what all is possible with file open modes, but I don't think > you can guarantee that once you've opened a file it won't change (unless > you unlink it, and know that noone else has an opened file handle to it). File open modes won't do it, and I don't think any thing else will do it using just POSIX behavior, either. Linux's mmap() used to support a DENY_WRITE flag, but it enabled DoS attacks, so it's gone. > It may be that by opening it in write mode you could ensure that noone else > modifies it (although I don't think this would work e.g. on nfs), It doesn't even work locally. -- Aaron Denney -><- _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
