Re: peekCString stack overflow

On Wed, Oct 01, 2003 at 05:34:47PM +0100, Alastair Reid wrote:
> 
> > Yes, I've run into this before.  In fact this is one of those tricky
> > problems where you can't quite get tail-recursion where you want it:
> > (pseudo-ish code follows)
> >
> >    peekCString ptr = do
> >      x <- peek ptr
> >      if x == '\0' then return [] else do
> >      xs <- peekCString (ptr + 1)
> >      return (x:xs)
> >
> > Any ideas?  I seem to recall the ML folks have a hack for dealing with
> > this.
> 
> Off the top of my head:
> 
> 1) Compute length of C string.
>    (As usual, need to use seq on the '+1' argument.)
> 2) Scan from right to left, constructing the list.

This scan is what peekArray does now.  We just need

peekArray0            :: (Storable a, Eq a) => a -> Ptr a -> IO [a]
peekArray0 marker ptr  = do
    size <- lengthArray0 marker ptr
    peekArray size ptr

and similarly for CStrings.