Sorry about the delay; I hadn't gotten around to seeing if I could reproduce it. Here is a working copy of the program which appears to work with GHC 7.10.2 on 64-bit Windows:
Thanks, that does indeed solve it the first bit. To try and make it a bit clearer what I'm after, I've put the stuff in a git repo: https://github.com/ndmitchell/ghc-process/blob/master/Main.hs Looking at Main.hs, there are three modes, Process (run ghc.exe 3 times), APIMake (the code you sent me), and APISingle (attempt to replicate the 3 ghc.exe invokations through the GHC API). The first two work perfectly, following Edward's tweaks. The final one fails at linking. So I have two questions: 1) Is there any way to do the two compilations sharing some cached state, e.g. loaded packages/.hi files, so each compilation goes faster. 2) Is there any way to do the link alone through the GHC API. Thanks, Neil