Sweep top-level buffers provide a history of previous user inputs,
similarly to other comint-mode derivatives such as
shell-mode. To insert the last input from the history at the
prompt, use M-p (comint-previous-input). See (emacs)Shell
History, for a full description of history related commands.
Minimum input length to record in the history of Sweep top-levels.
How to persist input history for top-levels across Emacs sessions.
The Sweep top-level history only records inputs whose length is at
least sweeprolog-top-level-min-history-length characters. This
user option is set to 3 by default, and should generally be set to at
least 2 to keep the history from being clobbered with single-character
inputs, which are common in the top-level interaction, for example
; as used to invoke backtracking.
Sweep can optionally persist top-level input history. The user option
sweeprolog-top-level-persistent-history controls if and where
top-levels store their persistent history: when this option is
non-nil, Sweep top-level buffers that you create read their
input history from a persistent history file, and write their history
back to it when you delete them. If this option is a string, it is
treated as a file name, and top-level buffers use that file to
persistent their input history. If it’s a function, it is called with
no arguments and should return either a file name for the persistent
history, or nil to disable persistent history for that
top-level buffer. The file name that this user option specifies can
be either absolute or relative, in which case it is expanded relative
to the default directory of the top-level buffer (see (emacs)File
Names). This option can also be a list of the form
(project rel def), in which case the persistent
history file that a top-level buffer uses depends on the current
project of the of that buffer (see (emacs)Projects). If there
is no current project, the top-level persistent history file is
def. Otherwise, the history file is rel relative to the
project’s root directory. You can leave def nil or omit
it entirely to disable persistent history for top-levels that are not
associated with any project. By default, this option is set to
nil which says not to keep persistent top-level history.