[Jscheme-user] New Module syntax

[Timothy J. H. <ti...@cs...>]

We've introduced a new module syntax into Jscheme.
This is a very lightweight change (mostly just syntax).

The new syntax for loading a jscheme file as a module is as follows:

(use-module MODULE)
(use-module MODULE SPECIFIER)
(use-module MODULE SPECIFIER SYMBOLS)
(use-module MODULE SPECIFIER SYMBOLS PREFIX)

where
     * MODULE is a either a filename, or a URL, or the name of a 
compiled Scheme module
     * SPECIFIER is one of the following:
           o 'import-procedures
           o 'import-macros
           o 'import
         and it specifies whether to import procedures, macros, or both. 
The default value is 'import.
     * SYMBOLS is either the symbol 'all or is a list of symbols. The 
default value is 'all. In the former
       case, all symbols defined in the module are imported to the 
current environment; in the latter case,
       only those symbols in the list are imported
     * PREFIX is a string which is prepended to each imported symbol 
from the module before that value
        is put into the current environment. The default value is the 
empty string "". Strings are never
        prepended to macros as macros are already changing the syntax...


Examples:

The following are all equivalent:
(use-module "elf/basic.scm")
(use-module "elf/basic.scm" 'import)
(use-module "elf/basic.scm" 'import 'all)
(use-module "elf/basic.scm" 'import 'all "")

The following examples show how to get more control over what is 
imported. You can import only procedures, or only macros, or import 
some subset of the procedure or macros.

(use-module "elf/basic.scm" 'import-procedures 'all)
(use-module "elf/basic.scm" 'import-procedures '(describe print))

(use-module "elf/basic.scm" 'import-macros 'all)
(use-module "elf/basic.scm" 'import-macros '(dotimes))

(use-module "elf/basic.scm" 'import '(describe print dotimes))


Finally, you can add arbitrary prefixes to the symbols that are 
imported, but prefixes are never applied to the macros.

(use-module "elf/basic.scm" 'import-procedures '(describe print) "elf:")
(use-module "elf/basic.scm" 'import-procedures '(describe print) "elf-")
(use-module "elf/basic.scm" 'import '(describe print dotimes) "elf:")

Modules are implemented by creating a new JScheme instance and loading 
the
specified files into that instance. Then copying the specified values 
to the
current environment and binding them to the specified symbols (possibly 
with prefixes).

Each module is cached when it is loaded and that same instance is used 
for
every "use-module".

Feedback is welcome.

Cheers,
---Tim---