Does not build on GHCJS

[oliver-batchelor]

Is it meant to? (ghcjs 0.2.0, ghc 8.0.2)

src/TextShow/Data/Text.hs:25:1: error:
Failed to load interface for ‘Data.Text.Foreign’

[RyanGlScott]

Hi @Saulzar. I've never been able to successfully build text-show with GHCJS (or most large Haskell projects, for that matter), so I'm certainly not surprised to learn that text-show doesn't build with GHCJS. If you know how to fix the issue, I'd gladly accept a patch.

[RyanGlScott]

OK, with the help of the folks at the #ghcjs IRC channel, I was able to get further than before. In fact, I was able to build the entirety of text-show-3.7.4 (the library, at least) with ghcjs-8.4.0.1, so perhaps this is simply an issue with an old version of ghcjs? This means I'd likely need to patch around the issue with some sort of CPP, but I don't know what that would be. If anyone reading this is familiar with ghcjs and knows the answer, your input would be appreciated.

[oliver-batchelor]

Hmm. I don't quite understand the error, maybe it's got nothing to do with text-show. Looks like that module should be present - but the interface files are missing in my environment (I'm using the reflex-platform).

In this enviornment the text version is 1.2.2.1 which definitely has this module, and I can import it just fine compiling with ghcjs --make.

[tgass]

I managed to build a project using text-show without any problems using stack and ghcjs-0.2.1.9008011_ghc-8.0.2. But as I'm switching to reflex-platform I ran into the described problem as well. So I'd assume it's a problem on the reflex-platform side.

[tgass]

There's now an issue in the reflex-platform project: reflex-frp/reflex-platform#466

[RyanGlScott]

OK. I'm not familiar with how reflex-platform does things. Is the necessary patching that has to be done to text-show something that can be upstreamed into this repo?

[tgass]

My current understanding is that nothing needs to be done in text-show but only in reflex-platform. text-show as it is compiles with ghcjs.

reflex-platform (when used with ghcjs) uses a fork of the text package that doesn't expose Data.Text.Foreign. And within reflex-platform there is already a place to adjust packages that are dependent on the forked text package. I'm currently looking into this and hopefully get a PR ready soon.

[RyanGlScott]

Are these patches tied to particular Hackage releases? My concern is that as text-show makes new releases, this reflex-platform patch will quickly become out-of-date and have to be maintained separately.

[tgass]

Here is the PR I made for reflex-platform (reflex-frp/reflex-platform#468). Ryan from the reflex project is asking if you'd be interested in taken it. Maybe just have a look.

[ryantrinkle]

@RyanGlScott I think it's really on reflex-platform to make this work, but if you would be willing to have a flag that chops out the Foreign stuff, that would definitely make our lives easier!

For what it's worth, the reason we use a non-standard text package is that, in our test cases, it saved almost 50% of the total memory of a running program compared with the standard text implementation. Browsers are much better at dealing with their own strings than at letting us reimplement them in terms of typed buffers!

[RyanGlScott]

Judging from the patch, it looks like the only part that's giving reflex-platform trouble is the I16 instance? To be honest, I have no particular reason for having that; I just blindly added it in an attempt to provide a TextShow instance to mirror every publicly accessible Show instance in the text. But I16 is really an internal component of text, and given a choice between workaround around the issue with CPP and just removing the I16 stuff altogether from text-show, I'm inclined to pick the latter (and wait until someone complains before adding it back). Does that sound like a reasonable course of action?

[ryantrinkle]

@RyanGlScott Thanks! I really appreciate you sorting this out :)

@tgass Want to strip out the patch in reflex-platform?

[tgass]

@ryantrinkle Sure. I'll just revert the commit and open a PR.

[RyanGlScott]

I've uploaded text-show-3.8 to Hackage with these changes.

[ryantrinkle]

@RyanGlScott Awesome; thanks!