Show HN: Lisp with copying GC in 537 lines of C (plus Lisp 1.5 on top)

This is cool. I wrote a similar Lisp but got stuck debugging my copying GC. The interaction between the Lisp environment chain and the C stack is tricky. I prefer something like this over Norvig's Lisp interpreter written in Python. Norvig's is good for understanding environments and eval/apply, but IMO it's cheating to use the host language's GC for allocations. I would add integers, even if it costs a few lines of code... using `itos` and re-parsing the string when…

It seemed appropriate to post this today. Did this while learning lisp about two years ago. Nothing special, a pretty straight forward implementation of the original LISP paper written while reading the paper, basically. It's difficult to describe the feeling when it clicks and the eval function comes together. All of the complexity of writing a language and an interpreter, reduced to what is basically one function that fits in a page. That is mind blowing. Edit: I realised this…

Is there something inherent to Lisp that allows it to be implemented in so little code? I believe I saw someone demonstrate that almost nothing in a Lisp implementation was written as a "built-in" language feature that required the underlying interpreter to provide the functionality.