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GNU Emacs Interface

There is an interface library, called xscheme, distributed with MIT Scheme and GNU Emacs, which facilitates running Scheme as a subprocess of Emacs. If you wish to use this interface, please install the version of `xscheme.el' that comes with MIT Scheme, as it is guaranteed to be correct for your version of Scheme.

To invoke Scheme from Emacs, use M-x run-scheme, which is defined when either of the libraries `scheme' or `xscheme' is loaded. You may give run-scheme a prefix argument, in which case it will allow you to edit the command line that is used to invoke Scheme. Do not remove the -emacs option!

Scheme will be started up as a subprocess in a buffer called *scheme*. This buffer will be in scheme-interaction-mode and all output from the Scheme process will go there. The mode line for the *scheme* buffer will have this form:

--**-*scheme*: 1 [Evaluator]           (Scheme Interaction: input)------

The first field, showing `1' in this example, is the level number.

The second field, showing `[Evaluator]' in this example, describes the type of REPL that is running. Other values include:

[Debugger]
[Where]

The mode after `Scheme Interaction' is one of:

`input'

Scheme is waiting for input.

`run'

Scheme is running an evaluation.

`gc'

Scheme is garbage collecting.

When xscheme is loaded, scheme-mode is extended to include commands for evaluating expressions (do C-h m in any scheme-mode buffer for the most up-to-date information):

ESC o

Evaluates the current buffer (xscheme-send-buffer).

ESC z

Evaluates the current definition (xscheme-send-definition). This is also bound to ESC C-x.

ESC C-z

Evaluates the current region (xscheme-send-region).

C-x C-e

Evaluates the expression to the left of point (xscheme-send-previous-expression). This is also bound to ESC RET.

C-c C-s

Selects the *scheme* buffer and places you at its end (xscheme-select-process-buffer).

C-c C-y

Yanks the most recently evaluated expression, placing it at point (xscheme-yank-previous-send). This works only in the *scheme* buffer.

The following commands provide interrupt capability:

C-c C-c

Like typing C-g when running Scheme without Emacs (xscheme-send-control-g-interrupt).

C-c C-x

Like typing C-c C-x when running Scheme without Emacs (xscheme-send-control-x-interrupt).

C-c C-u

Like typing C-c C-u when running Scheme without Emacs (xscheme-send-control-u-interrupt).

C-c C-b

Like typing C-c C-b when running Scheme without Emacs (xscheme-send-breakpoint-interrupt).

C-c C-p

Like evaluating (proceed) (xscheme-send-proceed).

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