when I realised I didn't have time to actually finish my own programming language (there was a big change needed in the type checker and it would have taken months with how much I can use a computer atm), I let claude something like 98% of the work, and it worked very well. The code comments are awful, but the code is ok. recently i have just let it have a go, and the code has grown more than I care for, but generally it has been doing well: https://github.com/bjoli/Bjolang