melange-decoders: melange backend

[actionshrimp]

• Combine bucklescript and melange implementations under js.
• This is breaking for bucklescript users: They now have to e.g. open Decoders.Js_json instead of Decoders.Bs_json

When finished this should fix #59.

TODO:

• update build to run the tests for the melange version
• try consuming the lib from another project via opam pin to check the install hack works properly

[mattjbray]

Is it possible to put all the js-related stuff under a melange/ subfolder? Something like:

• Move src-js -> melange/src
• Create melange/dune-project with (lang dune 3.8) and (using melange) (and revert /dune-project)
• Dune will create melange/decoders-mel.opam
• melange/src/dune does the (copy_files# ../../src/*.ml{,i})

[mattjbray]

Is it possible to put all the js-related stuff under a melange/ subfolder? Something like:

(And we'd need to figure out how to keep the bucklescript build working under this new layout too)

[mattjbray]

Nice.

[actionshrimp]

Naming the melange package melange-decoders (as opposed to decoders-mel) to match the melange convention described here: melange-re/melange#688

[actionshrimp]

Turns out we actually need (modes melange ..) for the decoders package itself in order to be able to use the Decoders sig in shared code - the shared code dune files will also need (modes melange ..) and (libraries decoders ..) for that to work.

So it looks like the melange dep and dune version bump is unavoidable. One temporary solution could be to leave this melange compatible version of decoders on a branch and rebase it off the main version. That way people who need melange support can pin the branch, and other people who don't use melange can use the regular version?

[actionshrimp]

Superceded by #65