LISP-FSRS

Implementation of the FSRS algorithm in Common Lisp and auto-transpiled to Emacs Lisp.

Usage

Common Lisp

CL-USER> (ql:quickload :lisp-fsrs)      ; Ensure you have cloned this repository into the `local-projects' directory under your Quicklisp installation root.
To load "lisp-fsrs":
  Load 1 ASDF system:
    lisp-fsrs
; Loading "lisp-fsrs"
(:LISP-FSRS)
CL-USER> (defparameter *weights* '(0.4072 1.1829 3.1262 15.4722 7.2102 0.5316 1.0651 0.0234 1.616 0.1544 1.0824 1.9813 0.0953 0.2975 2.2042 0.2407 2.9466 0.5034 0.6567))
*WEIGHTS*
CL-USER> (setf *weights* (coerce *weights* 'fsrs:weights))
#(0.4072 1.1829 3.1262 15.4722 7.2102 0.5316 1.0651 0.0234 1.616 0.1544 1.0824
  1.9813 0.0953 0.2975 2.2042 0.2407 2.9466 0.5034 0.6567)
CL-USER> (defparameter *scheduler* (fsrs:make-scheduler :weights *weights*))
*SCHEDULER*
CL-USER> (defparameter *card* (fsrs:make-card))
*CARD*
CL-USER> *card*
#S(LISP-FSRS:CARD
   :DUE @2024-12-11T23:29:20.562215+08:00
   :STABILITY 0.0
   :DIFFICULTY 0.0
   :ELAPSED-DAYS 0
   :SCHEDULED-DAYS 0
   :REPEATS 0
   :LAPSES 0
   :STATE :NEW
   :LAST-REVIEW NIL)
CL-USER> (setf *card* (fsrs:scheduler-review-card *scheduler* *card* :good))
#S(LISP-FSRS:CARD
   :DUE @2024-12-11T23:42:48.842234+08:00
   :STABILITY 3.1262
   :DIFFICULTY 5.3145776
   :ELAPSED-DAYS 0
   :SCHEDULED-DAYS 0
   :REPEATS 1
   :LAPSES 0
   :STATE :LEARNING
   :LAST-REVIEW @2024-12-11T23:32:48.842234+08:00)

To generate the fsrs package for Emacs after changing the code, ensure you are running the current Lisp session using sly in Emacs, then:

CL-USER> (ql:quickload :lisp-fsrs/emacs)
To load "lisp-fsrs/emacs":
  Load 1 ASDF system:
    lisp-fsrs/emacs
; Loading "lisp-fsrs/emacs"
[package lisp-fsrs.emacs]..
(:LISP-FSRS/EMACS)
CL-USER> (fsrs.emacs:translate-system)
NIL

Emacs Lisp

ELISP> (package-vc-install "https://github.com/open-spaced-repetition/lisp-fsrs.git")
t
ELISP> (setq weights [0.4072 1.1829 3.1262 15.4722 7.2102 0.5316 1.0651 0.0234 1.616 0.1544 1.0824 1.9813 0.0953 0.2975 2.2042 0.2407 2.9466 0.5034 0.6567])
[0.4072 1.1829 3.1262 15.4722 7.2102 0.5316 1.0651 0.0234 1.616 0.1544 1.0824 1.9813 0.0953 0.2975 2.2042 0.2407 2.9466 0.5034 0.6567]

ELISP> (setq scheduler (make-fsrs-scheduler :weights weights))
#s(fsrs-basic-scheduler :parameters #s(fsrs-parameters :request-retention 0.9 :maximum-interval 36500 :weights
                                                        [0.4072 1.1829 3.1262 15.4722 7.2102 0.5316 1.0651 0.0234 1.616 0.1544 1.0824 1.9813 0.0953 0.2975 2.2042 0.2407 2.9466 0.5034 0.6567]
                                                        :decay -0.5 :factor 0.23456790123456783))

ELISP> (setq card (make-fsrs-card))
#s(fsrs-card :due "2024-12-11T15:42:57Z" :stability 0.0 :difficulty 0.0 :elapsed-days 0 :scheduled-days 0 :repeats 0 :lapses 0 :state :new :last-review nil)

ELISP> (setq card (cl-nth-value 0 (fsrs-scheduler-review-card scheduler card :good)))
#s(fsrs-card :due "2024-12-11T15:53:27Z" :stability 3.1262 :difficulty 5.314577829570867 :elapsed-days 0 :scheduled-days 0 :repeats 1 :lapses 0 :state :learning :last-review "2024-12-11T15:43:27Z")