Using the GHC API to do a "dry run" of code compilation

Question

I'm working on a fairly simple text-editor for Haskell, and I'd like to be able to highlight static errors in code when the user hits "check."

Is there a way to use the GHC-API to do a "dry-run" of compiling a haskell file without actually compiling it? I'd like to be able to take a string and do all the checks of normal compilation, but without the output. The GHC-API would be ideal because then I wouldn't have to parse command-line output from GHC to highlight errors and such.

In addition, is it possible to do this check on a string, instead of on a file? (If not, I can just write it to a temp file, which isn't terribly efficient, but would work).

If this is possible, could you provide or point me to an example how how to do this?

This question ask the same thing, but it is from three years ago, at which time the answer was "GHC-API is new and there isn't good documentation yet." So my hope is that the status has changed.

EDIT: the "dry-run" restriction is because I'm doing this in a web-based setting where compilation happens server side, so I'd like to avoid unnecessary disk reads/write every time the user hits "check". The executable would just get thrown away anyways, until they had a version ready to run.

Answer 1

Just to move this to an answer, this already exists as ghc-mod, here's the homepage. This already has frontends for Emacs, Sublime, and Vim so if you need examples of how to use it, there are plenty. In essence ghc-mod is just what you want, a wrapper around the GHC API designed for editors.