wishlist: `foreign import javascript`, `JSVal`

[dmjio]

Per emscripten's documentation, it should now be possible to support calling into JavaScript. This might require creating a primitive type like JSVal, similar to what the new WASM / JS backends in GHC have.

https://ghc.gitlab.haskell.org/ghc/doc/users_guide/wasm.html#marshalable-types-and-jsval

foreign import javascript unsafe "alert" alert :: JSString -> IO ()

desugars into something like

EM_JS(void, call_alert, arg, {
  alert(arg);
});

This should allow us to build iOS and Android applications w/ MicroHS using JavaScript.

dmjio/miso#864

[augustss]

That looks doable. 🙂

[augustss]

There is some rudimentary support now. tests/ForImpJS.hs has a simple example.
It needs fleshing out with JSVal etc.
Currently Text cannot be passed back from JS to Haskell, but I'll fix that.

[dmjio]

Awesome, will test this on my branch. I wouldn't mind giving the JSVal implementation a shot, if you think it's appropriate to try that now.

[augustss]

Go ahead with JSVal!