docs for System.Posix.IO

[Glynn Clements]

Isaac Jones wrote:

> +-- |The 'createPipe' function creates a pair of connected file
> +-- descriptors. The first component is the fd to read from, the second
> +-- is the write end.  Although pipes may be bidirectional, this
> +-- behaviour is not portable and programmers should use two separate
> +-- pipes for this purpose.  May throw an exception if this is an
> +-- invalid descriptor.

It will only throw an exception if the system-wide or per-process
limits on the number of descriptors are exceeded. The Unix system call
can also raise EFAULT if the argument is invalid (does not point to
writable memory), but that shouldn't be possible from the Haskell
interface.

-- 
Glynn Clements <glynn at gclements.plus.com>