[GHC] #9164: Hunt down uses of `castPtr`

[GHC]

#9164: Hunt down uses of `castPtr`
-------------------------------------+------------------------------------
        Reporter:  nomeata           |            Owner:
            Type:  task              |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  libraries/base    |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------

Comment (by nomeata):

 > We can't change the type of hPutBuf and friends without potentially
 breaking code.

 Is there a stability guarantee on things in the `GHC` namespace? The
 module name tells me „this is lowevel stuff and may change“, at least
 between GHC releases and the usual `base` bump.

 Also, given that the docs state

 > hPutBuf hdl buf count writes count 8-bit bytes from the buffer buf to
 the handle hdl. It returns ().

 I’d say that `Ptr Word8` is fine – that is how `hPutBuf` uses it, and if I
 want to pass a `Ptr Double`, I have to think about whether that works.
 Having to call `castPtr` makes me think about it.

 (If you agree with this, then this might be a nice ZuriHac beginner task.)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9164#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler