Minimal Common Lisp s-expression parser in C

This is a small Common Lisp s-expression parser written in C as an academic exercise. Being a CMake project you can do the following to build and run after you have cloned the repo if you've got cmake and a C compiler installed on your PC:

cd lispp
mkdir build && cd build
cmake ..
cmake --build .

And then run a binary called lispp or lispp.exe to make it parse and print the parse tree for an s-expression. Here's what you'd see printed to stdout:

Lisp Code: (sum (gen-multiples (gen-series 1000) 3 5))

Parse Tree:
   <list>
      sum
      <list>
         gen-multiples
         <list>
            gen-series
            1000
         3
         5