GHCJS, repacked for stack lts8.0+

The ghcjs versions referred to in the stack docs do not cover stackage lts-8.0 + .

I have forked ghcjs, ghcjs-base and ghcjs-boot, altered a few patches and so forth and put together a working archive for use with stack snapshots lts-8.0+.

I have only tested these on linux, they have not been tested on Windows. If you'd like to use them on Windows then please give them a go, and let me know if you encounter issues.

IMPORTANT: note on Aeson

GHCJS depends on Aeson as a boot package. The version of Aeson in lts-8* includes some C code, and there is not currently a fully operational JS shim for it - see this issue for more information. Starting from 1.1.1.0 aeson offers a pure Haskell implementation via a flag. So from the perspective of ghcjs, you have two options -

1. Implement your own JS shim
2. Use aeson 1.1.1.0 +

I have gone for the second option for these distributions of ghcjs, so they come with aeson 1.1.1.0 as a boot package. This means that, firstly, you might need allow-newer: true in your stack.yaml, and secondly that stack will give you warnings about this, eg:

Ignoring that the GHCJS boot package "aeson" has a different version, 1.1.1.0, than the resolver's wanted version, 1.0.2.1

You may also get out of range warnings from other packages, like

WARNING: Ignoring out of range dependency (allow-newer enabled): aeson-1.1.1.0. reflex-dom requires: >=0.8 && <1.1

This is far from ideal - the api changes in aeson 1.1.0.0 are fortunately not massive but may break some packages (only the addition of instances for the UUID type should be an issue). Hopefully lts-9 will include a new version of aeson, and this issue will go away. Alternatively, we need to write a JS shim to support lts-8 properly.

Consistency with server side code

Bear in mind that if you are also compiling code with ghc (sharing code between server and client for instance) then you will probably want to use the same version of aeson in your server project stack.yaml, i.e. add - aeson-1.1.1.0 to your extra-deps section.

How to use

In your stack.yaml, instead of using eg http://ghcjs.tolysz.org/ghc-8.0-2017-01-11-lts-7.15-9007015.tar.gz simply link to the archive in this git repo. Eg:

resolver: lts-8.11
compiler: ghcjs-0.2.1.9008011_ghc-8.0.2
compiler-check: match-exact
setup-info:
  ghcjs:
    source:
      ghcjs-0.2.1.9008011_ghc-8.0.2:
        url: https://github.com/matchwood/ghcjs-stack-dist/raw/master/ghcjs-0.2.1.9008011.tar.gz
        sha1: a72a5181124baf64bcd0e68a8726e65914473b3b

The following snapshots are currently supported:

Resolver	Url	sha1
lts-8.11	https://github.com/matchwood/ghcjs-stack-dist/raw/master/ghcjs-0.2.1.9008011.tar.gz	a72a5181124baf64bcd0e68a8726e65914473b3b

Cautionary notes

While I have used these repacked versions of ghcjs to successfully compile working applications (including reflex and reflex-dom) they do fail a couple of tests - see this issue for more information ghcjs/ghcjs#571 .