What to do about NL

[odow]

It's an open question whether we should move the reading/writing of NL files from AMPLNLWriter over here. Thoughts?

https://github.com/JuliaOpt/AmplNLWriter.jl

[mlubin]

I'd say this is blocked by the lack of first-class support for nonlinear expressions in MOI.

[odow]

At the moment I just get the :expr_graph out of the NLPBlock

MathOptFormat.jl/src/MOF/nonlinear.jl

Lines 62 to 69 in 2615710

	# TODO(odow): is there a better way of checking if the NLPBlock is set?
	nlp_block = try
	MOI.get(model, MOI.NLPBlock())
	catch ex
	@assert isa(ex, KeyError)
	return # No NLPBlock set.
	end
	MOI.initialize(nlp_block.evaluator, [:ExprGraph])

And then query the expressions

MathOptFormat.jl/src/MOF/nonlinear.jl

Line 72 in 2615710

objective = MOI.objective_expr(nlp_block.evaluator)

[chriscoey]

I'd say this is blocked by the lack of first-class support for nonlinear expressions in MOI.

has there been any recent discussion on/proposals for this?

[odow]

Don't think so. Let's push 0.19 out the door first. However, first-class support could look like something very similar to how we store things in MOF.