* Use cabal-doctest
- Haskell build tools run in slightly different environments (meaning different
package databases are available).
- The nixpkgs build for polysemy-plugin is failing due to a missing package
database, which causes the doctest to fail (more information here:
https://github.com/NixOS/nixpkgs/issues/71164).
- By using cabal-doctest we can expose the Haskell packages required to the
doctests no matter the build tool we're using.
* Use cabal-doctest in polysemy, build on GHC 8.8.1
- Use @googleson78 's changes to build polysemy on GHC 8.8.1, with slight
modifications. The source distribution is now found in "dist-newstyle/sdist",
so we've updated the command to point at that folder. Additionally, cabal
v2-install doesn't support installing .tar.gz files in the same way v1-install
did, so updated the command to use "cabal v1-install".
- Modified polysemy to use "cabal-doctest" and so overcome issues with the
doctest tests (see issue #258, PR #265).
This PR has farmed out the type error machinery out to my new package https://github.com/isovector/type-errors. It's much nicer to work with, and a big red diff!
* Remove explicit loopbreakers, enable plugin
* Use uploaded version of `loopbreaker`
* Fix span of macro
* Disable plugin on GHC <8.6
* Add comment about use of plugin
* Separate unrelated conditions
This PR provides a single function withLowerToIO, which runs a desired Sem r effect all the way down to IO, without needing to know the natural transformation beforehand. It does it by running the desired code in a new thread, and shipping all of the unhandled effects back to the main thread. The main thread turns into an event loop for the duration of the withLowerToIO block.
This PR introduces the FCF machinery that will give us more control over writing type-level functions. It defines an IfStuck a b c tyfam that will leave b around if a is stuck, otherwise it will fcf-evaluate c. Everything is polykinded so we can stack these things together to make big logic chains to emit specific variables depending on what exactly is stuck.
This PR adds doctests allowing us to write tests for the custom type errors. Having this stuff reified in the test suite means we can iterate on the implementations and give much better QA.
