add on to what the other reply said, the second part is in pure c which means it likely gets far more gritty details as this book has to implement it's own hash

add on to what the other reply said, the second part is in pure c which means it likely gets far more gritty details as this book has to implement it's own hash map for storing the symbol table, since c doesn't have a huge standard library the way go does (note part 1 is in Java when he's building the AST runner instead of a bytecode compiler)