Messaging

Debugging evaluated code may be difficult, which is where the message special form comes in handy. It is used to print messages to the programmer during compilation.

    message "Debug point 1, foo=" foo;

    message "Type of var is " (typeOf var);

It can only handle some types of arguments, and they must be evaluated values. On the plus side, it is variadic.

You may use it as message::warning to give a warning to the programmer. Or, you may use it as message::error to return a compilation error, declaring the compilation a failure.

The first argument can be marked with ::loc to control the displayed code segment. This argument will not be printed and does not need to be an evaluated value.

    message::error x::loc "Value of argument was invalid.";

This attribute is mostly used when writing macros.