It looks like the echo bit ran fine on Windows, but for some reason the terminateProcess call (implicit in withCreateProcess) failed: https://ci.appveyor.com/project/snoyberg/process/build/1.0.186.

I'm also not sure of the motivation behind using an Integer value, instead of a CPid or similar.

Finally: there's a build failure with GHC 7.2.2: https://travis-ci.org/haskell/process/jobs/302093304.

The problem of withCreateProcess on Windows is unrelated to my changes. I opened #110 for this. The test for getPid now no longer uses withCreateProcess for this reason.

I chose Integer as return type as a lazy solution to have a type that can represent the PID on all systems (Int32 or possibly larger on POSIX, DWORD on Windows.. which is an unsigned 32bit integer). I knew it was not the optimal solution and did it anyway. I resolved that by adding a Pid type to System.Process that is an alias for the native type that represents the PID.

I saw that your tests run on msys. That explains why i had no success in plain cmd.exe. With a minor adjustment the test now passes on all systems (OSX builds are still pending... but i am confident).

Thanks for the update and the other bug report. One final request: can you update the changelog and add a @since comment to the Haddock?

@simonmar Would you mind having a quick look at this one and making sure I'm not missing some reason why this function would be problematic in the public API?

Updated the comments and changelog.

Thanks!