Error compiling with clang

[ridulfo]

Hi!
I enjoyed the project! Great job! 👏

Just wanted to mention that we get

lisp.c:219:5: error: call to undeclared function 'strip_spaces'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declarat
ion]
    strip_spaces(expression);
    ^

running gcc *.c -o lisp -std=c99 on

> clang -v
Apple clang version 15.0.0 (clang-1500.1.0.2.5)
Target: arm64-apple-darwin23.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Adding a header-file for parser.h and including it in lisp.c fixed this. 🙂

[Kreijstal]

fixed by #3