To use our 1.3 I/O, you should compile and link using a `-fhaskell-1.3' flag.
You should consult the PROPOSED 1.3-I/O standard. GHC 0.26 implements the "December 1994" draft, which we distribute in `ghc/docs/io-1.3/'.
Alternatively, you could grab the "June 1995" draft, from `pub/haskell/report/', on `ftp.dcs.glasgow.ac.uk'. The main December--June change that you need to know about is: many of the I/O functions have been removed from `Prelude*' interfaces (no import required) and put into `Lib*' interfaces (import required).
GHC 0.26 still provides the I/O functions via `Prelude.hi' (no import required). Ignore the "June draft" pleadings for `import LibIO', and you'll be fine.
There is no guarantee that the final 1.3 proposal will look anything like the current DRAFT. It ain't a standard until the fat committee sings.
For interaction with our non-standard `PrimIO', including `_ccall_'s. we also provide:
-- impedance matching stuff ioToPrimIO :: IO a -> PrimIO a