Thank you for your contribution to GHC!
Please take a few moments to verify that your commits fulfill the following:
are either individually buildable or squashed
have commit messages which describe what they do (referring to Notes and tickets using
#NNNNsyntax when appropriate)
have added source comments describing your change. For larger changes you likely should add a Note and cross-reference it from the relevant places.
add a testcase to the testsuite.
This implements GHC proposal #314.
If you have any questions don't hesitate to open your merge request and inquire
in a comment. If your patch isn't quite done yet please do add prefix your MR