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12.1 Introduction to REDUCE Run mode

REDUCE Run mode provides the following facilities for running REDUCE:

• input editing and flexible re-execution of previous input;
• flexible browsing of all input and output;
• syntax highlighting of prompts, input, warning and error messages, and trace output;
• bracket and delimiter highlighting or matching as in REDUCE mode;
• easy REDUCE package loading, source file input and module compilation;
• seamless integration with source files being edited using REDUCE edit mode, including easy input of statements, procedure definitions, arbitrary regions or the whole file to REDUCE;
• optional automatic starting of REDUCE;
• menu access to many facilities;
• all other standard Emacs facilities, such as printing part or all of the interaction buffer.

These facilities include many of those offered by other REDUCE interfaces, but REDUCE IDE does not currently provide typeset quality display of mathematical output.

REDUCE Run mode is a subsidiary library to REDUCE mode and when loaded it hooks itself into and cooperates closely with REDUCE mode.

REDUCE Run mode is built on top of the general command-interpreter-in-a-buffer (comint) mode and so shares a common base functionality and a common set of key bindings with all modes derived from comint mode. This makes these modes easier to use. (Among these, shell mode is likely to be the most familiar. See Interactive Inferior Shell in The Emacs Editor. In fact, REDUCE Run mode is based on the standard library inf-lisp by Olin Shivers. See Running an External Lisp in The Emacs Editor.)

For further documentation on the functionality provided by comint mode and the hooks available for customizing it, see the comint customization group and the file comint.el.

Note that, by default, in comint mode the whole interaction buffer is editable, which applies also to REDUCE Run mode, unlike most other REDUCE interfaces, in which previous input and output cannot be changed. This can be particularly disconcerting when deleting erroneous input “back to the prompt” because, by default, the prompt itself can also be deleted. This can be prevented by customizing the option comint-prompt-read-only. The comint customization group can be accessed via a link in the REDUCE Run customization group.

Implementation Note

REDUCE is eventually run by the Emacs function make-process (see see (elisp)Asynchronous Processes), which is implemented in C code. It runs programs directly if possible, but uses the default shell to run shell scripts or batch files. It looks up relative program file names in exec-path (see see (elisp)Subprocess Creation). By default, it directs stdout and stderr to the process buffer. It uses pipes for communication on Microsoft Windows, but pseudo-terminals (ptys) on other platforms.