Chapel: Feature Request: Primer on C / Chapel interoperability

[buddha314]

I would find it very useful to see a complete example of calling Chapel modules / files / functions from C and linked from the Primers page.

There are a few things of particular interest

1. Calling Chapel from C
2. Passing matrices / arrays (sparse or dense) back and forth, perhaps with boost vectors on the C end.
3. Importing full Chapel modules
4. How to link to Chapel using CMake (maybe a find_chapel() macro?)
5. Perhaps a github repo with a reference directory structure

[mppf]

Just to be sure, do you already know about https://chapel-lang.org/docs/technotes/libraries.html ?

[lydia-duncan]

I think this is a reasonable request. I probably won't get to it until closer to feature freeze, but definitely will before next release

[buddha314]

Just to be sure, do you already know about https://chapel-lang.org/docs/technotes/libraries.html ?

Yes, I do, thanks for checking in! It seems much of this information is spread around and would be useufl to a crappy programmer like me to see it laid out in one place, especially on the matrix / vec ops.

"How do I always re-appear right before code freeze?" You ask. Talent, skill, dedication... :)

[lydia-duncan]

At least this time you are three months ahead of it! XD

[lydia-duncan]

I have a start of this over at this branch

Things that aren't covered yet:

• [ ] extern records
  
  
  
  • [ ] with omitted fields
  
  
• [ ] renaming extern symbols using the "external name" syntax
• [ ] comments describing how to include the code that defines the extern symbols
  
  
  
  • [ ] via require statements
  
  
  • [ ] via the compile line command
  
  
• [ ] types that are already available without the user having to write extern type declarations (i.e. c_int, etc)
• [ ] passing arrays back and forth
  
  
  
  • [ ] c_ptr
  
  
  • [ ] c_array
  
  
  • [ ] chpl_external_array
  
  
  • [ ] chpl_opaque_array
  
  
• [ ] update primers/README
• [ ] update primers/Makefile
• [ ] something similar for Python
• [ ] something similar for Fortran