Port yaml package

[indegro]

I tryied to use yaml library and

etlas install --dependencies-only
produces the error

Build log ( C:\Users\ddushyn\AppData\Roaming\etlas\logs\eta-0.7.0.1\yaml-0.8.25.1-2DHGKZz01fp2JRDlxu0yer.log ):
Preprocessing library for yaml-0.8.25.1..
Building library for yaml-0.8.25.1..
[ 1 of 10] Compiling Text.Libyaml ( Text\Libyaml.hs, dist\build\Text\Libyaml.jar )
eta.exe: panic! (the 'impossible' happened)
(Eta version 0.7.0b1):
tcCheckFIType: Unsupported calling convention.
ccall unsafe "value yaml_alias_event_initialize"

[rahulmutt]

We will eventually need yaml for the eta-ffi (FFI Generator) work. If you are interested in helping port it, you can start using the eta-snakeyaml package which provides bindings for the SnakeYAML Java library.

[indegro]

@rahulmutt In my case yaml packae is a transitive dependency.
I would like to try to port it. Could you please guide me through this process?

Are there any links that help me do that?

[rahulmutt]

No links yet, but here are some steps:

1. etlas get yaml
   Fetchs the package and extracts it into your current directory. It'll be of the form yaml-[version].
2. cd yaml-[version]
3. git init && git add . && git commit -m "First"
   Sets up the reference point for the patch.
4. etlas build
   This is the step you'll be coming back to quite a bit. Basically, you keep patching stuff until it builds.
   Some general tips:

• Get rid of any dependencies on unix or Win32 in the cabal file.
• Remove all C-related fields from the cabal file like c-sources, include-dirs, pkgconfig-depends.
• Remove any platform-specific conditional fields. Say you see stuff like if os(windows), etc.
  You should remove it.
• You'll need to replace foreign import ccall statements with foreign import java and this
  requires you to understand the original C code and the Java code that you want to replace it with (can be from a library if you wish).
• Sometimes, you may have to re-design the internal API in order to make it easier to bind to the
  Java API. There is no problem in doing this, but the main rule is that you should not change
  the type signatures of exported functions/types.

4. Rinse and repeat from step 3 until it builds successfully.

See the instructions here to create and submit the patch once you're done.

Feel free to reach out here or on Gitter if you get stuck.