Nevermind, I saw the tutorial. I think I was confused by the “Parallel” in the title…
julia> f_det = eval(ModelingToolkit.build_function( det(u), u ))
#6 (generic function with 1 method)
julia> A = rand(3,3);
julia> det(A)
-0.04382988531989483
julia> f_det(A)
-0.04382988531989484