cross-compile for scala.js

[erikerlandson]

I know absolutely nothing about scala.js or its ecosystem.

If I'm lucky, sbt-crossproject would allow me to fake this.
https://github.com/portable-scala/sbt-crossproject

[cquiroz]

I could try to do this, I've done a bunch of scala.js projects and we may need coulomb

[erikerlandson]

@cquiroz if you want to take a stab at it, please feel free! I'm hoping it's mostly additional targets in sbt, and corresponding in travis ci

[cquiroz]

It is blocked on spire that hasn't been released yet for scala.js 1.0

[erikerlandson]

crossref: typelevel/spire#888

[erikerlandson]

Looks like the "real" problem is the archival of machinist
typelevel/spire#888 (comment)

[erikerlandson]

@cquiroz I believe spire 0.17.0-RC1 is building with scalaJS 1.x

[cquiroz]

Yes, I'm waiting for a release

[erikerlandson]

https://github.com/typelevel/spire/releases/tag/v0.17.0-RC1

[erikerlandson]

scala-steward updated to spire 0.17.0-RC1, which I merged, so if you rebase from develop ScalaJS 1.x should in theory work now

[cquiroz]

Yes I'm updating the build, will send a PR soon

[cquiroz]

Actually I found a show stopper. coulomb uses WeakTypeTags which aren't available on scala.js. I'm not very familiar with them, I dont know if coulomb could use something else

[erikerlandson]

I can try ClassTag
scala-js/scala-js#50 (comment)

Mostly I'm using them to provide default names based on the name of a type.

Another possible approach would be to not support defaults that require WeakTypeTag or TypeTag, or not support them in scala.js - the code would need some refactoring to support that kind of dual functionality.

Or possibly punt to macros. those are supported IIUC

Maybe a dedicated implicit GetTypeName, that could punt to a macro or just invoke WeakTypeTag. I was excited about getting rid of the scala-2.x macros and I'm not eager to bring them back, but maybe if they were only invoked for scala.js ... ?

Scala's support for "conditional compilation" is pretty awkward, but I see people do it.

If we are ultimately forced to use macros, this is nice and compact.
https://stackoverflow.com/a/15649874/3669757

[cquiroz]

@tpolecat sugested to use shapeless Typeable to get the names. Some uses are in libs that are jvm only like pureconfig thus we wouldn't need to change them

[cquiroz]

I can try todo it and make sure they'd run in scala.js

[erikerlandson]

@tpolecat sugested to use shapeless Typeable to get the names.

Sounds like a good approach, shapeless is already a dependency. If it works, I'm happy to use it everywhere. I recently migrated everything to WeakTypeTag for consistency.

It might be worth using a shim GetTypeName in case this needs to be changed yet again in the future. GetTypeName could call Typeable for now.

[erikerlandson]

closing with #97
QuantityParser and its deps are not supported in scalaJS in their current form, that will require a future redesign