Insert or remove spaces around point to such that the next Prolog token starts at a column distanced from the beginning of the previous token by a multiple of four columns.
Whether to add sweeprolog-align-spaces as the first element of
cycle-spacing-actions in Sweep Prolog mode buffers. Defaults
to t.
To insert or update whitespace around point, use the command M-x
sweeprolog-align-spaces. As an example, consider a Sweep Prolog mode
buffer with the following contents, where ∗ designates the
location of the cursor:
foo :- ( if ;∗
Calling M-x sweeprolog-align-spaces inserts three spaces, to
yield the expected layout:
foo :- ( if ; ∗
In Emacs 29, you can extend the command M-x cycle-spacing via a
list of callback functions specified by the variable
cycle-spacing-actions. Sweep leverages this facility and adds
sweeprolog-align-spaces as the first action of
cycle-spacing. To inhibit sweeprolog-mode from doing
so, set the user option sweeprolog-enable-cycle-spacing to nil.
Moreover, in Emacs 29 cycle-spacing is bound by default to
M-SPC, which means that all you need to do to align
if-then-else and similar constructs is to type M-SPC after
the first token.
In Emacs prior to version 29, you can bind
sweeprolog-align-spaces to M-SPC directly by adding
the following lines to Emacs’s initialization file (see (emacs)Init
File).
(eval-after-load 'sweeprolog '(define-key sweeprolog-mode-map (kbd "M-SPC") #'sweeprolog-align-spaces))