c0de

Feedback from the tutorials of c0de.at.

• PRINT writes BOOLEAN values as TRUE and FALSE, as the handbook says (⊕ still writes true and false).
• RETURN raises INVALID_ARGUMENT for an error the program made with a code below 1000, like RAISE; an error received from a CALL can still be passed on.
• Program runner: it knows the types and functions of c0de/minecraft, so programs that include it are validated completely and run until they call the library, which raises INVALID_ARGUMENT ("needs the game"). It reports every problem once, sorted by line. docs/runner.md describes the values of input.
• Schema of the program files: c0de-program.schema.json, attached to the GitHub release, describes the YAML files of the disk drive, so editors can check hand-written files. Every file is checked against it before it is read; a file that doesn't match is refused with a message that names the first problem and where it is.
• Safe program names: wherever a program crosses a disk (copying, saving, loading, receiving it on the server, building it), its name must be a valid name. Names with path separators, invisible or right-to-left characters or look-alike letters of other scripts are refused, so a program can't hide its real name or write outside the folder c0de.
• Documentation: the guide, the reference and the handbooks answer what the tutorials of c0de.at had to find out by trying (indexes, the minus sign, precedence of AND and OR, errors as constants, EXIT and results, TICKS and the time of day, FORMAT, the time zone of TIMER and WEEK, POSITION, ENTITY and ITEM_STACK, FIND_ENTITIES, PID.activator, the instruments of SOUND, SAY, FROM_JSON). PI has a page of its own.