Switch stanc.ml to Core_kernel Command module from Arg module about stanc3 HOT 7 CLOSED

RealWorldOCaml writes

The Arg module
The Arg module is from the OCaml standard library, which is used by the compiler itself to handle its command-line interface. Command is generally more featureful than Arg (mainly via support for subcommands, the step combinator to transform inputs, and help generation), but there’s absolutely nothing wrong with using Arg either. You can use the Command.Spec.flags_of_args_exn function to convert Arg specifications into ones compatible with Command. This is quite often used to help port older non-Core code into the Core standard library world.

@seantalts , what is the priority of this issue? Should it be listed under the initial release milestone? In what way does the current command line interface not suffice?

from stanc3.

Re: why: I think we'll see synergies by switching entirely to Core_kernel and using it whenever we need something it supports. They have the same code and doc standards, interface aesthetics, etc. And I found the Arg thing a bit weird at first - very side-effect-y, for example.

I think it will probably work and this shouldn't block an initial release, but we can keep this here as a good first issue.

from stanc3.

OK! Makes sense!

from stanc3.

Is the idea then to fold Debugging.ml into stanc.ml with those arguments held inside the definition of options? Or would we like Debugging to continue to be used as it is now?

from stanc3.

We talked a little about this at the meeting - I think we want to move away from the global references used for config and debug flags and what not and instead pass config records to the frontend, middle, and backend. So I think eventually we'd like to get rid of Debugging.ml but we could do that separately from this PR if that's easier.

from stanc3.

I just realized we don't even have access to the Jane st Command module yet - it's in Core_kernel 0.12.0 and up, and we're on 0.11.1. We could upgrade, but then ocamlformat gets upgraded and touches a bunch of files in a silly way. @enetsee we should probably wait until after your refactor for this.

from stanc3.

This is theoretically possible with #1019 merged, but I'm not sure we can do this still. So far as I can tell, Core_kernel's version of Command has no Command.run function -- that's only in Core, which I believe cannot be cross compiled. This seems really strange to me - Arg works fine after all.

from stanc3.