Although the postgresql-libpq binding has supported both COPY IN and COPY OUT for some time now, this functionality wasn't available to postgresql-simple without mucking around in the Internal module to call libpq functions on your own. I just now fixed that. The interface I went with ultimately mimics the libpq interface rather closely, albeit with many simplifications. I did consider offering fold-like combinators, and while they would certainly be much more convenient for some use cases, they also introduce a number of complications, such as dealing with exceptions. If anybody's interested in reviewing these latest patches, I'd appreciate it. I suppose the one thing I'm most unsure about is exactly which exceptions should be raised under various conditions. https://github.com/lpsmith/postgresql-simple/commit/491247f687fcbfd30c8b0f50... https://github.com/lpsmith/postgresql-simple/commit/4cfcdbee22a0cb1fb7985988... Best, Leon