;; This is an example of what an interaction with the talkative meta-circular
;; evaluator might look like.  Anything not identified by a comment as being
;; typed by the user is output from the program.

;; First the user types the following line and evaluates in normal scheme:
(initialize-evaluator)
  Creating new frame 1 as global environment binding (nil t + - * / = < > 1+ -1+ cons car cdr atom? eq? null? not) to (() #T (primitive +) (primitive -) (primitive *) (primitive /) (primitive =) (primitive <) (primitive >) (primitive 1+) (primitive -1+) (primitive cons) (primitive car) (primitive cdr) (primitive atom?) (primitive eq?) (primitive null?) (primitive not))

;; Now, in "mini-scheme", the user types and evaluates this definition:
(define fact
  (lambda (n)
    (cond ((= n 0) 1)
          (else (* (fact (- n 1))
                   n)))))
Evaluating (define fact (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n))))) in environment 1
  Evaluating (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) in environment 1
  Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
No binding found for fact in frame 1
Adding binding to (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
Result is fact
;Value: fact

;; The user types the next line and evaluates it, still in mini-scheme
(fact 4)
Evaluating (fact 4) in environment 1
  Evaluating 4 in environment 1
  Result is 4
  Evaluating fact in environment 1
  Found binding for fact in frame 1
  Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
Applying (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1) to (4)
Creating new frame 2 with parent 1 binding (n) to (4)
Evaluating (cond ((= n 0) 1) (else (* (fact (- n 1)) n))) in environment 2
  Evaluating (= n 0) in environment 2
    Evaluating 0 in environment 2
    Result is 0
    Evaluating n in environment 2
    Found binding for n in frame 2
    Result is 4
    Evaluating = in environment 2
    No binding found for = in frame 2
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (4 0)
  Result is ()
Evaluating (* (fact (- n 1)) n) in environment 2
  Evaluating n in environment 2
  Found binding for n in frame 2
  Result is 4
  Evaluating (fact (- n 1)) in environment 2
    Evaluating (- n 1) in environment 2
      Evaluating 1 in environment 2
      Result is 1
      Evaluating n in environment 2
      Found binding for n in frame 2
      Result is 4
      Evaluating - in environment 2
      No binding found for - in frame 2
      Found binding for - in frame 1
      Result is (primitive -)
    Applying (primitive -) to (4 1)
    Result is 3
    Evaluating fact in environment 2
    No binding found for fact in frame 2
    Found binding for fact in frame 1
    Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
  Applying (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1) to (3)
  Creating new frame 3 with parent 1 binding (n) to (3)
  Evaluating (cond ((= n 0) 1) (else (* (fact (- n 1)) n))) in environment 3
    Evaluating (= n 0) in environment 3
      Evaluating 0 in environment 3
      Result is 0
      Evaluating n in environment 3
      Found binding for n in frame 3
      Result is 3
      Evaluating = in environment 3
      No binding found for = in frame 3
      Found binding for = in frame 1
      Result is (primitive =)
    Applying (primitive =) to (3 0)
    Result is ()
  Evaluating (* (fact (- n 1)) n) in environment 3
    Evaluating n in environment 3
    Found binding for n in frame 3
    Result is 3
    Evaluating (fact (- n 1)) in environment 3
      Evaluating (- n 1) in environment 3
        Evaluating 1 in environment 3
        Result is 1
        Evaluating n in environment 3
        Found binding for n in frame 3
        Result is 3
        Evaluating - in environment 3
        No binding found for - in frame 3
        Found binding for - in frame 1
        Result is (primitive -)
      Applying (primitive -) to (3 1)
      Result is 2
      Evaluating fact in environment 3
      No binding found for fact in frame 3
      Found binding for fact in frame 1
      Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
    Applying (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1) to (2)
    Creating new frame 4 with parent 1 binding (n) to (2)
    Evaluating (cond ((= n 0) 1) (else (* (fact (- n 1)) n))) in environment 4
      Evaluating (= n 0) in environment 4
        Evaluating 0 in environment 4
        Result is 0
        Evaluating n in environment 4
        Found binding for n in frame 4
        Result is 2
        Evaluating = in environment 4
        No binding found for = in frame 4
        Found binding for = in frame 1
        Result is (primitive =)
      Applying (primitive =) to (2 0)
      Result is ()
    Evaluating (* (fact (- n 1)) n) in environment 4
      Evaluating n in environment 4
      Found binding for n in frame 4
      Result is 2
      Evaluating (fact (- n 1)) in environment 4
        Evaluating (- n 1) in environment 4
          Evaluating 1 in environment 4
          Result is 1
          Evaluating n in environment 4
          Found binding for n in frame 4
          Result is 2
          Evaluating - in environment 4
          No binding found for - in frame 4
          Found binding for - in frame 1
          Result is (primitive -)
        Applying (primitive -) to (2 1)
        Result is 1
        Evaluating fact in environment 4
        No binding found for fact in frame 4
        Found binding for fact in frame 1
        Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
      Applying (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1) to (1)
      Creating new frame 5 with parent 1 binding (n) to (1)
      Evaluating (cond ((= n 0) 1) (else (* (fact (- n 1)) n))) in environment 5
        Evaluating (= n 0) in environment 5
          Evaluating 0 in environment 5
          Result is 0
          Evaluating n in environment 5
          Found binding for n in frame 5
          Result is 1
          Evaluating = in environment 5
          No binding found for = in frame 5
          Found binding for = in frame 1
          Result is (primitive =)
        Applying (primitive =) to (1 0)
        Result is ()
      Evaluating (* (fact (- n 1)) n) in environment 5
        Evaluating n in environment 5
        Found binding for n in frame 5
        Result is 1
        Evaluating (fact (- n 1)) in environment 5
          Evaluating (- n 1) in environment 5
            Evaluating 1 in environment 5
            Result is 1
            Evaluating n in environment 5
            Found binding for n in frame 5
            Result is 1
            Evaluating - in environment 5
            No binding found for - in frame 5
            Found binding for - in frame 1
            Result is (primitive -)
          Applying (primitive -) to (1 1)
          Result is 0
          Evaluating fact in environment 5
          No binding found for fact in frame 5
          Found binding for fact in frame 1
          Result is (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1)
        Applying (compound-procedure (lambda (n) (cond ((= n 0) 1) (else (* (fact (- n 1)) n)))) pointing-to-environment 1) to (0)
        Creating new frame 6 with parent 1 binding (n) to (0)
        Evaluating (cond ((= n 0) 1) (else (* (fact (- n 1)) n))) in environment 6
          Evaluating (= n 0) in environment 6
            Evaluating 0 in environment 6
            Result is 0
            Evaluating n in environment 6
            Found binding for n in frame 6
            Result is 0
            Evaluating = in environment 6
            No binding found for = in frame 6
            Found binding for = in frame 1
            Result is (primitive =)
          Applying (primitive =) to (0 0)
          Result is #T
        Evaluating 1 in environment 6
        Result is 1
        Evaluating * in environment 5
        No binding found for * in frame 5
        Found binding for * in frame 1
        Result is (primitive *)
      Applying (primitive *) to (1 1)
      Result is 1
      Evaluating * in environment 4
      No binding found for * in frame 4
      Found binding for * in frame 1
      Result is (primitive *)
    Applying (primitive *) to (1 2)
    Result is 2
    Evaluating * in environment 3
    No binding found for * in frame 3
    Found binding for * in frame 1
    Result is (primitive *)
  Applying (primitive *) to (2 3)
  Result is 6
  Evaluating * in environment 2
  No binding found for * in frame 2
  Found binding for * in frame 1
  Result is (primitive *)
Applying (primitive *) to (6 4)
Result is 24
;Value: 24

;; The next definition is also typed in and evaluated in mini-scheme:
(define make-counter
  (lambda (c)
    (lambda ()
      (set! c (+ c 1))
      c)))
Evaluating (define make-counter (lambda (c) (lambda () (set! c (+ c 1)) c))) in environment 1
  Evaluating (lambda (c) (lambda () (set! c (+ c 1)) c)) in environment 1
  Result is (compound-procedure (lambda (c) (lambda () (set! c (+ c 1)) c)) pointing-to-environment 1)
No binding found for make-counter in frame 1
Adding binding to (compound-procedure (lambda (c) (lambda () (set! c (+ c 1)) c)) pointing-to-environment 1)
Result is make-counter
;Value: make-counter

(define c (make-counter 0))
Evaluating (define c (make-counter 0)) in environment 1
  Evaluating (make-counter 0) in environment 1
    Evaluating 0 in environment 1
    Result is 0
    Evaluating make-counter in environment 1
    Found binding for make-counter in frame 1
    Result is (compound-procedure (lambda (c) (lambda () (set! c (+ c 1)) c)) pointing-to-environment 1)
  Applying (compound-procedure (lambda (c) (lambda () (set! c (+ c 1)) c)) pointing-to-environment 1) to (0)
  Creating new frame 7 with parent 1 binding (c) to (0)
  Evaluating (lambda () (set! c (+ c 1)) c) in environment 7
  Result is (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7)
No binding found for c in frame 1
Adding binding to (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7)
Result is c
;Value: c

;; Now the user tries (c) out in mini-scheme:
(c)
Evaluating (c) in environment 1
  Evaluating c in environment 1
  Found binding for c in frame 1
  Result is (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7)
Applying (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7) to ()
Creating new frame 8 with parent 7 binding () to ()
  Evaluating (set! c (+ c 1)) in environment 8
    Evaluating (+ c 1) in environment 8
      Evaluating 1 in environment 8
      Result is 1
      Evaluating c in environment 8
      No binding found for c in frame 8
      Found binding for c in frame 7
      Result is 0
      Evaluating + in environment 8
      No binding found for + in frame 8
      No binding found for + in frame 7
      Found binding for + in frame 1
      Result is (primitive +)
    Applying (primitive +) to (0 1)
    Result is 1
  No binding found for c in frame 8
  Found binding for c in frame 7
  Changing binding to 1
  Result is 1
Evaluating c in environment 8
No binding found for c in frame 8
Found binding for c in frame 7
Result is 1
;Value: 1

;; Now the user types and evaluates (c) a second time in mini-scheme:
(c)
Evaluating (c) in environment 1
  Evaluating c in environment 1
  Found binding for c in frame 1
  Result is (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7)
Applying (compound-procedure (lambda () (set! c (+ c 1)) c) pointing-to-environment 7) to ()
Creating new frame 9 with parent 7 binding () to ()
  Evaluating (set! c (+ c 1)) in environment 9
    Evaluating (+ c 1) in environment 9
      Evaluating 1 in environment 9
      Result is 1
      Evaluating c in environment 9
      No binding found for c in frame 9
      Found binding for c in frame 7
      Result is 1
      Evaluating + in environment 9
      No binding found for + in frame 9
      No binding found for + in frame 7
      Found binding for + in frame 1
      Result is (primitive +)
    Applying (primitive +) to (1 1)
    Result is 2
  No binding found for c in frame 9
  Found binding for c in frame 7
  Changing binding to 2
  Result is 2
Evaluating c in environment 9
No binding found for c in frame 9
Found binding for c in frame 7
Result is 2
;Value: 2

;; Now the user types in a re-definition of fact and evaluates in mini-scheme:
(define fact
  (lambda (n)
    (define fact-times
      (lambda (n p)
        (cond ((= n 0) p)
              (else (fact-times (-1+ n) (* n p))))))
    (fact-times n 1)))
Evaluating (define fact (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1))) in environment 1
  Evaluating (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1)) in environment 1
  Result is (compound-procedure (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1)) pointing-to-environment 1)
Found binding for fact in frame 1
Changing binding to (compound-procedure (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1)) pointing-to-environment 1)
Result is fact
;Value: fact

;; Now the user types (fact 4) and evaluates this test in mini-scheme:
(fact 4)
Evaluating (fact 4) in environment 1
  Evaluating 4 in environment 1
  Result is 4
  Evaluating fact in environment 1
  Found binding for fact in frame 1
  Result is (compound-procedure (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1)) pointing-to-environment 1)
Applying (compound-procedure (lambda (n) (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) (fact-times n 1)) pointing-to-environment 1) to (4)
Creating new frame 10 with parent 1 binding (n) to (4)
  Evaluating (define fact-times (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))))) in environment 10
    Evaluating (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) in environment 10
    Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
  No binding found for fact-times in frame 10
  Adding binding to (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
  Result is fact-times
Evaluating (fact-times n 1) in environment 10
  Evaluating 1 in environment 10
  Result is 1
  Evaluating n in environment 10
  Found binding for n in frame 10
  Result is 4
  Evaluating fact-times in environment 10
  Found binding for fact-times in frame 10
  Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
Applying (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10) to (4 1)
Creating new frame 11 with parent 10 binding (n p) to (4 1)
Evaluating (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))) in environment 11
  Evaluating (= n 0) in environment 11
    Evaluating 0 in environment 11
    Result is 0
    Evaluating n in environment 11
    Found binding for n in frame 11
    Result is 4
    Evaluating = in environment 11
    No binding found for = in frame 11
    No binding found for = in frame 10
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (4 0)
  Result is ()
Evaluating (fact-times (-1+ n) (* n p)) in environment 11
  Evaluating (* n p) in environment 11
    Evaluating p in environment 11
    Found binding for p in frame 11
    Result is 1
    Evaluating n in environment 11
    Found binding for n in frame 11
    Result is 4
    Evaluating * in environment 11
    No binding found for * in frame 11
    No binding found for * in frame 10
    Found binding for * in frame 1
    Result is (primitive *)
  Applying (primitive *) to (4 1)
  Result is 4
  Evaluating (-1+ n) in environment 11
    Evaluating n in environment 11
    Found binding for n in frame 11
    Result is 4
    Evaluating -1+ in environment 11
    No binding found for -1+ in frame 11
    No binding found for -1+ in frame 10
    Found binding for -1+ in frame 1
    Result is (primitive -1+)
  Applying (primitive -1+) to (4)
  Result is 3
  Evaluating fact-times in environment 11
  No binding found for fact-times in frame 11
  Found binding for fact-times in frame 10
  Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
Applying (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10) to (3 4)
Creating new frame 12 with parent 10 binding (n p) to (3 4)
Evaluating (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))) in environment 12
  Evaluating (= n 0) in environment 12
    Evaluating 0 in environment 12
    Result is 0
    Evaluating n in environment 12
    Found binding for n in frame 12
    Result is 3
    Evaluating = in environment 12
    No binding found for = in frame 12
    No binding found for = in frame 10
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (3 0)
  Result is ()
Evaluating (fact-times (-1+ n) (* n p)) in environment 12
  Evaluating (* n p) in environment 12
    Evaluating p in environment 12
    Found binding for p in frame 12
    Result is 4
    Evaluating n in environment 12
    Found binding for n in frame 12
    Result is 3
    Evaluating * in environment 12
    No binding found for * in frame 12
    No binding found for * in frame 10
    Found binding for * in frame 1
    Result is (primitive *)
  Applying (primitive *) to (3 4)
  Result is 12
  Evaluating (-1+ n) in environment 12
    Evaluating n in environment 12
    Found binding for n in frame 12
    Result is 3
    Evaluating -1+ in environment 12
    No binding found for -1+ in frame 12
    No binding found for -1+ in frame 10
    Found binding for -1+ in frame 1
    Result is (primitive -1+)
  Applying (primitive -1+) to (3)
  Result is 2
  Evaluating fact-times in environment 12
  No binding found for fact-times in frame 12
  Found binding for fact-times in frame 10
  Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
Applying (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10) to (2 12)
Creating new frame 13 with parent 10 binding (n p) to (2 12)
Evaluating (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))) in environment 13
  Evaluating (= n 0) in environment 13
    Evaluating 0 in environment 13
    Result is 0
    Evaluating n in environment 13
    Found binding for n in frame 13
    Result is 2
    Evaluating = in environment 13
    No binding found for = in frame 13
    No binding found for = in frame 10
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (2 0)
  Result is ()
Evaluating (fact-times (-1+ n) (* n p)) in environment 13
  Evaluating (* n p) in environment 13
    Evaluating p in environment 13
    Found binding for p in frame 13
    Result is 12
    Evaluating n in environment 13
    Found binding for n in frame 13
    Result is 2
    Evaluating * in environment 13
    No binding found for * in frame 13
    No binding found for * in frame 10
    Found binding for * in frame 1
    Result is (primitive *)
  Applying (primitive *) to (2 12)
  Result is 24
  Evaluating (-1+ n) in environment 13
    Evaluating n in environment 13
    Found binding for n in frame 13
    Result is 2
    Evaluating -1+ in environment 13
    No binding found for -1+ in frame 13
    No binding found for -1+ in frame 10
    Found binding for -1+ in frame 1
    Result is (primitive -1+)
  Applying (primitive -1+) to (2)
  Result is 1
  Evaluating fact-times in environment 13
  No binding found for fact-times in frame 13
  Found binding for fact-times in frame 10
  Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
Applying (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10) to (1 24)
Creating new frame 14 with parent 10 binding (n p) to (1 24)
Evaluating (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))) in environment 14
  Evaluating (= n 0) in environment 14
    Evaluating 0 in environment 14
    Result is 0
    Evaluating n in environment 14
    Found binding for n in frame 14
    Result is 1
    Evaluating = in environment 14
    No binding found for = in frame 14
    No binding found for = in frame 10
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (1 0)
  Result is ()
Evaluating (fact-times (-1+ n) (* n p)) in environment 14
  Evaluating (* n p) in environment 14
    Evaluating p in environment 14
    Found binding for p in frame 14
    Result is 24
    Evaluating n in environment 14
    Found binding for n in frame 14
    Result is 1
    Evaluating * in environment 14
    No binding found for * in frame 14
    No binding found for * in frame 10
    Found binding for * in frame 1
    Result is (primitive *)
  Applying (primitive *) to (1 24)
  Result is 24
  Evaluating (-1+ n) in environment 14
    Evaluating n in environment 14
    Found binding for n in frame 14
    Result is 1
    Evaluating -1+ in environment 14
    No binding found for -1+ in frame 14
    No binding found for -1+ in frame 10
    Found binding for -1+ in frame 1
    Result is (primitive -1+)
  Applying (primitive -1+) to (1)
  Result is 0
  Evaluating fact-times in environment 14
  No binding found for fact-times in frame 14
  Found binding for fact-times in frame 10
  Result is (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10)
Applying (compound-procedure (lambda (n p) (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p))))) pointing-to-environment 10) to (0 24)
Creating new frame 15 with parent 10 binding (n p) to (0 24)
Evaluating (cond ((= n 0) p) (else (fact-times (-1+ n) (* n p)))) in environment 15
  Evaluating (= n 0) in environment 15
    Evaluating 0 in environment 15
    Result is 0
    Evaluating n in environment 15
    Found binding for n in frame 15
    Result is 0
    Evaluating = in environment 15
    No binding found for = in frame 15
    No binding found for = in frame 10
    Found binding for = in frame 1
    Result is (primitive =)
  Applying (primitive =) to (0 0)
  Result is #T
Evaluating p in environment 15
Found binding for p in frame 15
Result is 24
;Value: 24