GHC as a library - getting output from GHCI

[Simon Marlow]

Matthew Danish wrote:
> On Thu, May 10, 2007 at 09:34:53AM +0100, Simon Marlow wrote:
>> And we do have support for this in GHC.
>>
>> $ ghci
>>    ___         ___ _
>>   / _ \ /\  /\/ __(_)
>>  / /_\// /_/ / /  | |    GHC Interactive, version 6.7, for Haskell 98.
>> / /_\\/ __  / /___| |    http://www.haskell.org/ghc/
>> \____/\/ /_/\____/|_|    Type :? for help.
>>
>> Loading package base ... linking ... done.
>> Prelude> :m + System.IO
>> Prelude System.IO> h <- openFile "out" WriteMode
>> {handle: out}
>> Prelude System.IO> GHC.Handle.hDuplicateTo h stdout
>> -- as this point, GHCi goes quiet: I type ":quit"
>> $ cat out
>> Prelude System.IO> :quit
>> Leaving GHCi.
>>
>> Cheers,
>> 	Simon
> 
> 
> Is there any way to create a handle which dumps its input into a
> string or memory buffer of some kind?  I only know of the ability to
> open file/socket handles, and a quick browse of GHC/Handle.hs doesn't
> seem to indicate anything else.  I'm not counting
> createPipe/fdToHandle because that is not portable.

Sadly not at the moment.  Our Handle implementation is currently always backed 
by a file descriptor.  It would certainly be possible (though not easy) to 
extend it in this direction.

Cheers,
	Simon