Support for macros returning macros?

[kiranandcode]

Sorry for the multiple questions. This follows on from @mflatt 's earlier response to supporting += operators.

Is it possible to write a macro that automatically generates dot definitions for a class?

Here's what I've tried so far:

defn.macro 'object_with_fields $name (($field, $get_field, $set_field), ...)':
  'class $name($field,...):
    opaque
    internal $_name

    constructor ($field, ...):
      super($field, ...)

    dot $(@{'}) $('$') left . $field $(@{'}) :
      ~tail: tail
      match tail                        //other cases omitted for now
      | ~else:
         $(@{'})block:
           def b :~ $_name =  @{$} left
           b . $field
         $(@{'})
    ...
    '

The above fails with the error dot: bad syntax, which I assume is because ${@{'}) isn't actually what I want, and the code I'm emitting isn't right:

// dot: bad syntax
//  in: (dot "'" (op $) left (op |.|) x "'" (block ,,,

[mflatt]

The trick to nesting quotes in quotes is to use '« for the outer opening quote and »' for the outer closing quote:

defn.macro 'object_with_fields ....':
  '«class $name($field,...):
      ....
      dot '$('$') left . $field':
        ....
      ...
      »'

You can use '«...»' in place of '...' anywhere, but the idea of using non-ASCII characters is that immediate quote nesting is relatively rare, so maybe it's ok to make that a little more difficult to type (but « and » are Option-\ and Shift-Option-\ on a U.S. Mac keyboard), and that way we don't use more valuable characters and combinations.