rs-0.11.0 — Docstrings, triple-quoted strings, and `marslang symbols`#

Functions, families, and methods can carry documentation, strings can span lines, and the interpreter can describe a program to an editor.

Triple-quoted strings#

mars

banner = """Marslang
  says "hello"
  to\tyou""";

A string in triple double quotes keeps its line breaks, indentation, and inner " characters; escapes still work. Lines after it keep their numbers, so an error further down still names the right line.

@Decorator.docstring#

mars

takepkg std.Decorator;

@Decorator.docstring("""
    A circle, measured from its radius.

    area() uses pi to five places.
""")
family Circle{
    @Decorator.docstring("The area inside the circle.")
    func area() => 3.14159 * me.r * me.r;
}

Decorators now work above top-level functions and families as well as methods. @Decorator.docstring takes one string and removes the indentation its lines share, so it can be indented with the code. It changes nothing at runtime. @Decorator.private and @Decorator.subclass still apply to methods only, and say so when written elsewhere.

marslang symbols#

marslang symbols file.mars prints, as JSON, every function, family, and method with its parameters, source lines, and docstring, and every variable with its scope and type: the annotation when there is one, otherwise the type its first value shows, marked as inferred. --stdin reads the source from standard input, so an editor can describe unsaved text. The VS Code extension uses it to show types and docstrings on hover.

Changed#

Errors from reading the source now start with the line, like other compile errors: line 2: unterminated string starting at column 9 instead of unterminated string at 2:9, and an unclosed string is reported where it opens rather than where the file ends.
The decorator marker list is docstring, private, subclass, static, class, overload.

Validation#