https://youtu.be/NszLQNROdw0

peg-solitaire.rkt

#lang racket

(require redex)

(define-term initial-board [[· · ◼︎ ◼︎ ◼︎ · ·]
                            [· · ◼︎ ◼︎ ◼︎ · ·]
                            [◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎]
                            [◼︎ ◼︎ ◼︎ ◻︎ ◼︎ ◼︎ ◼︎]
                            [◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎]
                            [· · ◼︎ ◼︎ ◼︎ · ·]
                            [· · ◼︎ ◼︎ ◼︎ · ·]])

(define-language peg-solitaire
  [board ::=
         [[position position position position position position position]
          [position position position position position position position]
          [position position position position position position position]
          [position position position position position position position]
          [position position position position position position position]
          [position position position position position position position]
          [position position position position position position position]]]
  [position ::= ◻︎ ◼︎ ·])

#;(redex-match peg-solitaire board (term initial-board))

(define play (reduction-relation peg-solitaire
                                 #:domain board
                                 #:codomain board
                                 (--> [any_1 ...
                                       [any_3 ... ◼︎ ◼︎ ◻︎ any_4 ...]
                                       any_2 ...]
                                      [any_1 ...
                                       [any_3 ... ◻︎ ◻︎ ◼︎ any_4 ...]
                                       any_2 ...]
                                      →)
                                 (--> [any_1 ...
                                       [any_3 ... ◻︎ ◼︎ ◼︎ any_4 ...]
                                       any_2 ...]
                                      [any_1 ...
                                       [any_3 ... ◼︎ ◻︎ ◻︎ any_4 ...]
                                       any_2 ...]
                                      ←)
                                 (--> [any_1 ...
                                       [any_3 ..._9 ◼︎ any_4 ...]
                                       [any_5 ..._9 ◼︎ any_6 ...]
                                       [any_7 ..._9 ◻︎ any_8 ...]
                                       any_2 ...]
                                      [any_1 ...
                                       [any_3 ... ◻︎ any_4 ...]
                                       [any_5 ... ◻︎ any_6 ...]
                                       [any_7 ... ◼︎ any_8 ...]
                                       any_2 ...]
                                      ↓)
                                 (--> [any_1 ...
                                       [any_3 ..._9 ◻︎ any_4 ...]
                                       [any_5 ..._9 ◼︎ any_6 ...]
                                       [any_7 ..._9 ◼︎ any_8 ...]
                                       any_2 ...]
                                      [any_1 ...
                                       [any_3 ... ◼︎ any_4 ...]
                                       [any_5 ... ◻︎ any_6 ...]
                                       [any_7 ... ◻︎ any_8 ...]
                                       any_2 ...]
                                      ↑)))

#;(apply-reduction-relation play (term initial-board))
#;(apply-reduction-relation play (term  ((· · ◼︎ ◼︎ ◼︎ · ·)
                                         (· · ◼︎ ◼︎ ◼︎ · ·)
                                         (◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎)
                                         (◼︎ ◼︎ ◼︎ ◻︎ ◻︎ ◻︎ ◼︎)
                                         (◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎ ◼︎)
                                         (· · ◼︎ ◼︎ ◼︎ · ·)
                                         (· · ◼︎ ◼︎ ◼︎ · ·))))

#;(traces play (term initial-board))
(stepper play (term initial-board))