Resolve "Parser simplification" ✨️

Closes #107 🐔️👍️

🦀️🍰🦀️🍰🦀️🍰

* chore(std, examples): fix syntax

* chore(parser): change test to fit new syntax

* fix(parser): remove the use of comma as argument separator, for more consistency

* fix(parser): simpler, (hopefully) equivalent grammar