How to create a new host language

[bentxt]

Hi,
I would like to develop new host languages for ribbit and could use some help here.

As a long term goal its the host for Swift and Java I aim for. But I thought I first go with a dynamic language like Perl host so that I can use the Python host as template. Does that makes sense?

As a first step I would like to enable the debug and tracing features that seam to be already implemented. But here I already fail, How do I enable and use them in the compiled .py code?

Thanks
Ben

[bentxt]

I see that I enable debugging with ./rsc -di expansion. Do I understand correctly that it is basically a feature like many things in ribbit? What about tracing?

The thing I look for is basic print based debugging. Meaning I'm able to insert some print statements into the rvm.py code in order to figure out, how the host code works.

[leo-ard]

Hi Ben! Yes, I think you approach is good, starting simple and going more complex after this. Perl is a good target, although I believe a student is already implementing one for the Compiler class at UdeM (but if its just for learning, it's perfect!). Another choice could be Ruby, as the one in the repo is not yet implemented and just printing the hello bytecode: https://github.com/udem-dlteam/ribbit/blob/leo-ard/document-contributing/src/host/rb/rvm.rb

I started to develop some ressources for writing a new RVM. It's currently not in the main branch as I didn't finish the document yet, but there is still some very useful information: https://github.com/udem-dlteam/ribbit/blob/leo-ard/document-contributing/CONTRIBUTING.md. One of the most useful ressource in my opinion is the annotated hello.py RVM from this branch: https://github.com/udem-dlteam/ribbit/blob/leo-ard/document-contributing/src/host/py/hello.py. It explains up to the decode/run functions.

Your first goal should be to have an HELLO! RVM, meaning a file that can interpret the following bytecode that prints HELLO! to the stdout: );'u?>vD?>vRD?>vRA?>vRA?>vR:?>vR=!(:lkm!':lkv6y. Once you have this, you can start running the core tests. If they all pass, you have a woking core RVM! Tell me which RVM you want to start with (perl or ruby) and I can create a little starting pack in the host directory (so the tests are easy to run!). I meant to create scripts for this but it's not yet ready.

For the debugging/tracing, it's mostly handled by the RVMs. When compiling a program with -f+ debug, the compiler will only include all symbols name so that the RVM can easily print them, and it will enable all code within @@(feature debug and )@@. If you look at the normal python RVM, the code to print the current status of the program is done within those tags. You could do something similar with your RVM. The -di expansion option prints the scheme code after expansion, but this is mostly used to debug the output from the compiler.

Thanks for taking the time to look into this, if you have other questions don't hesitate! Tell me which RVM you want to start with and I'll create a starting pack:)