Well I did it in Scheme, but there's no reason it wouldn't have worked in Julia. If you're interested in this, the relatively recent Software Design for Flexibi

Well I did it in Scheme, but there's no reason it wouldn't have worked in Julia. If you're interested in this, the relatively recent Software Design for Flexibility by Chris Hanson and GJS [1] has a pretty good couple of chapters on creating a generic procedure system (and a lot of other really cool things). Edit: In fact, it has an example doing just this example: symbolic alternative evaluation. Where they get the closed form solution from a simple differential equation solver without changing any code in the solver. Now that I think about it, this idea is pretty much how automatic differentiation works in Julia. (Really everything in Julia.) You can look at the libraries Flux.jl and Zygote.jl. There are probably more now, I've been out of the Julia ecosystem for about a year or so. [1] https://mitpress.mit.edu/9780262045490/ https://mitpress.mit.edu/9780262045490/