mode for editing .km files (The Knowledge Machine, a Lisp-based
reasoning engine)
reddit / emacs

----------------------------------------------------------------------
EdwardCoffin · 2022-11-15 14:32

Edit: to make it clear, I am asking whether anyone knows of a mode
that would be better than lisp-mode.

I'm currently using lisp-mode for [The Knowledge
Machine](https://www.cs.utexas.edu/~mfkb/km.html) .km files, but it is
not indenting things the way the documentation shows it.  For example,
this is how the handbook represents the following:

    (parts has
      (instance-of (Slot))
      (domain (Physobj))
      (range (Physobj))
      (cardinality (1-to-N))
      (inverse (part-of))
      (subslots (mechanical-parts body-parts)))
    (mechanical-parts has
      (instance-of (Slot))
      (superslots (parts)))
    (wheel-count has
      (instance-of (Slot))
      (domain (Vehicle))
      (range (Integer))
      (cardinality (N-to-1)))

but when I indent the region containing it in lisp-mode, I get:

    (parts has
           (instance-of (Slot))
           (domain (Physobj))
           (range (Physobj))
           (cardinality (1-to-N))
           (inverse (part-of))
           (subslots (mechanical-parts body-parts)))
    (mechanical-parts has
                      (instance-of (Slot))
                      (superslots (parts)))
    (wheel-count has
                 (instance-of (Slot))
                 (domain (Vehicle))
                 (range (Integer))
                 (cardinality (N-to-1)))

the problem (stuff pushed way out to the right) is worse for concepts
that have longer names than `wheel-count`.  I'm sure that there must
be, if not a dedicated KM mode that I simply cannot find, an existing
mode that can be customized to produce the handbook formatting, but I
can't find it.

Edit 2: added a couple of more example declarations, all from page 12
of the [KM user
manual](https://www.cs.utexas.edu/users/mfkb/km/userman.pdf) (pdf).

----------------------------------------------------------------------
usaoc · 2022-11-15 16:28

The easiest way is to put `1` to `wheel-count`’s `lisp-indent-
function` property.  This works the same as [`indent` declaration in `
defmacro`](https://www.gnu.org/software/emacs/manual/html_node/elisp/I
ndenting-Macros.html).

----------------------------------------------------------------------
EdwardCoffin · 2022-11-15 16:51

The problem is wheel-count is more akin to a specific `defun`.  There
are 50+ such declarations in the km file I am looking at.  If there
was a way to cause `lisp-indent-function` to key off of the second
argument in the s-exp, the `has`, I could put 1 in `has`'s `lisp-
indent-function` property and that would work.

Most of the declarations in a km file are of the form:

    (<entity name> has
        ;; a bunch of declarations)

and

    (every <entity name> has
        ;; a bunch of declarations)

I can at least get the `every` declarations with this method, but
there are a lot of the former type too.  I might have to just override
`lisp-indent-function` with a custom version for KM, but I'd rather
avoid that if possible.

----------------------------------------------------------------------
usaoc · 2022-11-15 17:03

Well, it seems like [setting `lisp-indent-offset`](https://www.gnu.org
/software/emacs/manual/html_node/emacs/Lisp-Indent.html) will be a
better idea then?  You can [set it file-locally](https://www.gnu.org/s
oftware/emacs/manual/html_node/elisp/File-Local-Variables.html) or
[define a derived mode](https://www.gnu.org/software/emacs/manual/html
_node/elisp/Derived-Modes.html) that [sets it buffer-locally](https://
www.gnu.org/software/emacs/manual/html_node/elisp/Creating-
Buffer_002dLocal.html).  Otherwise you’ll have to define your own
indent function.

----------------------------------------------------------------------
EdwardCoffin · 2022-11-15 17:09

Perfect, thanks a lot.  I just put it in the -*- header, which is way
better than figuring out how to write an indent function.