Edwin Support for External Schemes

I’m pleased to announce an alpha release of support for using Edwin to interact with external Schemes. This is similar to the way Emacs can interact with REPLs from languages other than Emacs Lisp.

The code is available at http://github.com/rmloveland/edwin-external-scheme. The repository contains two Edwin modes, “External Scheme mode” and “External Scheme REPL mode”.


“External Scheme REPL mode” allows you to interact with an external Scheme REPL’s process from Edwin in the same way you would interact with a shell using `#\M-x shell’. Load the file `external-scheme-repl.scm’ and enter the command `#\M-x external-scheme-repl’. You’ll be asked to enter the name of the external Scheme you’d like to run, and away you go.

External Scheme mode inherits from Edwin’s Scheme mode for all of its formatting and editing commands, but provides its own commands for sending expressions to a running external Scheme REPL, if one exists.

Load the file `external-scheme-mode.scm’ and enter the command `#\M-x external-scheme-mode’ in a buffer containing Scheme code that you want to send to the external Scheme. Right now you can run only one external Scheme REPL, so be sure that the code you’re sending is going to be understood by that Scheme. It’s a simple matter of programming to extend this to multiple external Scheme buffers if you care to.


Right now you may run only one external Scheme REPL at a time. Any Scheme buffers in External Scheme mode will send their eval’d code to that REPL.

Finally, note that files containing Scheme code are automatically opened by Edwin in its own Scheme mode, no matter what Scheme they’re written in, so you’ll need to do `#\M-x external-scheme-mode’.


Finally, why bother? Isn’t MIT Scheme good enough? The answer is yes: it’s great. However, I often write scripts using Scheme Shell due to its tight integration with UNIX and excellent process notation. I could already write these programs in Emacs, but Edwin is my preferred editor.

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