DSL with macros?

[briochemc]

Maybe worth reworking the interface to be simpler and yielding more efficient code.
I was thinking of something along the lines of

1. Define tracers, e.g., DIP, DOP, POP, DFe, DO₂, maybe with a macro like

   @define_tracers DIP DOP POP DFe DO₂

2. Then define functions and who they apply to, maybe something like

   @add_BGC_sink DIP → uptake : 1 / τ * DIP^2 / (DIP + k) * (z ≤ zₑ)
   @add_BGC_source POP : σ * uptake
   @add_BGC_source DOP : (1-σ) * uptake
   @add_BGC_transfer DOP → DIP : kDOP * DOP
   @add_BGC_transfer POP → DOP : kPOP * POP
   @add_restoring DIP : DIPgeo τgeo
   @add_external_source DFe : aeolian_DFe_source
   etc.

3. Then be able to pack/unpack the tracers and also create efficient inplace F (as suggested in AIBECS F is quite slower (5x) than handmade F #10)

[briochemc]

Somehow it might be nice to have a struct detailing the model generated as well, i.e., containing metadata about the model. See DSL branch for trials.

[briochemc]

Also might be good to replace the current parameter API into something like

@parameters "MyParams" begin
    a | 1.0u"m/s"
    b | 2.0u"m^2"
end

Hopefully this issue in FieldMetadata.jl will help!