learning koans

- refreshed understanding of lexical vs. dynamic binding
  https://gigamonkeys.com/book/variables.html
- was taught CASE as simpler variant of COND

lisp-koans/koans/asserts.lisp

@@ -28,38 +28,38 @@
 ;;; Sometimes, you will be asked to provide values that are equal to something.
 
 (define-test fill-in-the-blanks
-  (assert-equal ____ 2)
-  (assert-equal ____ 3.14)
-  (assert-equal ____ "Hello World"))
+  (assert-equal 2 2)
+  (assert-equal 3.14 3.14)
+  (assert-equal "Hello World" "Hello World"))
 
 ;;; Sometimes, you will be asked to say whether something is true or false,
 ;;; In Common Lisp, the canonical values for truth and falsehood are T and NIL.
 
 (define-test assert-true
-  (assert-true ____))
+  (assert-true t))
 
 (define-test assert-false
-  (assert-false ____))
+  (assert-false nil))
 
+;; could use C-x C-e (sly-eval-last-expression) to eval just (= 34 34) to check whether T or NIL returns
 (define-test true-or-false
-  (true-or-false? ____ (= 34 34))
-  (true-or-false? ____ (= 19 78)))
+  (true-or-false? t (= 34 34))
+  (true-or-false? nil (= 19 78)))
 
 ;;; Since T and NIL are symbols, you can type them in lowercase or uppercase;
 ;;; by default, Common Lisp will automatically upcase them upon reading.
 
 (define-test upcase-downcase
   ;; Try inserting a lowercase t here.
-  (assert-equal ____ T)
+  (assert-equal t T)
   ;; Try inserting an uppercase NIL here.
-  (assert-equal ____ nil))
+  (assert-equal NIL nil))
 
 ;;; Sometimes, you will be asked to provide a part of an expression that must be
 ;;; either true or false.
 
 (define-test a-true-assertion
-  (assert-true (= ____ (+ 2 2))))
+  (assert-true (= 4 (+ 2 2))))
 
 (define-test a-false-assertion
-  (assert-false (= ____ (+ 2 2))))
-
+  (assert-false (= 3 (+ 2 2))))

lisp-koans/koans/atoms-vs-lists.lisp

@@ -19,25 +19,25 @@
 (define-test list-or-atom
   ;; The function LISTP will return true if the input is a list.
   ;; The function ATOM will return true if the input is an atom.
-  (true-or-false? ____ (listp '(1 2 3)))
-  (true-or-false? ____ (atom '(1 2 3)))
-  (true-or-false? ____ (listp '("heres" "some" "strings")))
-  (true-or-false? ____ (atom '("heres" "some" "strings")))
-  (true-or-false? ____ (listp "a string"))
-  (true-or-false? ____ (atom "a string"))
-  (true-or-false? ____ (listp 2))
-  (true-or-false? ____ (atom 2))
-  (true-or-false? ____ (listp '(("first" "list") ("second" "list"))))
-  (true-or-false? ____ (atom '(("first" "list") ("second" "list")))))
+  (true-or-false? t (listp '(1 2 3)))
+  (true-or-false? nil (atom '(1 2 3)))
+  (true-or-false? t (listp '("heres" "some" "strings")))
+  (true-or-false? nil (atom '("heres" "some" "strings")))
+  (true-or-false? nil (listp "a string"))
+  (true-or-false? t (atom "a string"))
+  (true-or-false? nil (listp 2))
+  (true-or-false? t (atom 2))
+  (true-or-false? t (listp '(("first" "list") ("second" "list"))))
+  (true-or-false? nil (atom '(("first" "list") ("second" "list")))))
 
 (define-test the-duality-of-nil
   ;; The empty list, NIL, is unique in that it is both a list and an atom.
-  (true-or-false? ____ (listp nil))
-  (true-or-false? ____ (atom nil)))
+  (true-or-false? t (listp nil))
+  (true-or-false? t (atom nil)))
 
 (define-test keywords
   ;; Symbols like :HELLO or :LIKE-THIS are keywords. They are treated
   ;; differently in Lisp: they are constants that always evaluate to themselves.
-  (true-or-false? ____ (equal :this-is-a-keyword :this-is-a-keyword))
-  (true-or-false? ____ (equal :this-is-a-keyword ':this-is-a-keyword))
-  (true-or-false? ____ (equal :this-is-a-keyword :this-is-also-a-keyword)))
+  (true-or-false? t (equal :this-is-a-keyword :this-is-a-keyword))
+  (true-or-false? t (equal :this-is-a-keyword ':this-is-a-keyword))
+  (true-or-false? nil (equal :this-is-a-keyword :this-is-also-a-keyword)))

lisp-koans/koans/basic-macros.lisp

@@ -22,43 +22,49 @@
         (c (copy-seq "I am Tom.")))
     ;; A place may be a variable.
     (setf a 1000)
-    (assert-equal ____ a)
+    (assert-equal 1000 a)
     ;; A place may be a part of some list.
     (setf (first b) 10)
-    (assert-equal ____ b)
+    (assert-equal '(10 20 30 40 50) b)
     ;; A place may be a character in a string.
     ;; The #\x syntax denotes a single character, 'x'.
     (setf (char c 5) #\B
           (char c 7) #\b)
-    (assert-equal ____ c)
+    (assert-equal "I am Bob." c)
     ;; There are other kinds of places that we will explore in the future.
     ))
 
+;;; looks like COND is much stronger
+;; while CASE only tests with some kind of equasion?
+;; with destructuringom as well?
+;; http://www.lispworks.com/documentation/HyperSpec/Body/m_case_.htm
+;; nope, not desctructuring, but can have check on belonging to a set
+;; http://www.lispworks.com/documentation/HyperSpec/Body/m_cond.htm
 (define-test case
     ;; CASE is a simple pattern-matching macro, not unlike C's "switch".
     ;; It compares an input against a set of values and evaluates the code for
     ;; the branch where a match is found.
     (let* ((a 4)
-         (b (case a
+           (b (case a                   ; and the book have tought COND
                 (3 :three)
                 (4 :four)
                 (5 :five))))
-    (assert-equal ____ b))
+      (assert-equal :four b))
   ;; CASE can accept a group of keys.
   (let* ((c 4)
          (d (case c
               ((0 2 4 6 8) :even-digit)
               ((1 3 5 7 9) :odd-digit))))
-    (assert-equal ____ d)))
+    (assert-equal :even-digit d)))
 
 (defun match-special-cases (thing)
   ;; T or OTHERWISE passed as the key matches any value.
   ;; NIL passed as the key matches no values.
   ;; These symbols need to passed in parentheses.
   (case thing
-    (____ :found-a-t)
-    (____ :found-a-nil)
-    (____ :something-else)))
+    ((t) :found-a-t)
+    ((nil) :found-a-nil)
+    (otherwise :something-else)))
 
 (define-test special-cases-of-case
   ;; You need to fill in the blanks in MATCH-SPECIAL-CASES.
@@ -71,9 +77,9 @@
   (flet ((cartoon-dads (input)
            (case input
              ;; Fill in the blanks with proper cases.
-             ____
-             ____
-             ____
+             ((:bart :lisa)  :homer)
+             (:stewie :peter)
+             (:stan  :randy)
              (:this-one-doesnt-happen :fancy-cat)
              (t :unknown))))
     (assert-equal (cartoon-dads :bart) :homer)
@@ -91,14 +97,14 @@
          (string-copy (copy-seq string)))
     ;; The above means that two distinct strings will not be the same under EQL,
     ;; even if they have the same contents.
-    (true-or-false? ____ (eql string string-copy))
-    (true-or-false? ____ (equal string string-copy))
+    (true-or-false? nil (eql string string-copy))
+    (true-or-false? t (equal string string-copy))
     ;; The above also means that CASE might give surprising results when used on
     ;; strings.
     (let ((match (case string
                    ("A string" :matched)
                    (t :not-matched))))
-      (assert-equal ____ match))
+      (assert-equal :not-matched match))
     ;; We will explore this topic further in the EQUALITY-DISTINCTIONS lesson.
     ))
 
@@ -109,4 +115,4 @@
          (result (cond ((> number 0) :positive)
                        ((< number 0) :negative)
                        (t :zero))))
-    (assert-equal ____ result)))
+    (assert-equal :positive result)))

lisp-koans/koans/evaluation.lisp

@@ -19,30 +19,30 @@
 
 (define-test function-names
   ;; In these examples, +, -, *, and / are function names.
-  (assert-equal ____ (+ 2 3))
-  (assert-equal ____ (- 1 3))
-  (assert-equal ____ (* 7 4))
-  (assert-equal ____ (/ 100 4)))
+  (assert-equal 5 (+ 2 3))
+  (assert-equal -2 (- 1 3))
+  (assert-equal 28 (* 7 4))
+  (assert-equal 25 (/ 100 4)))
 
 (define-test numberp
   ;; NUMBERP is a predicate which returns true if its argument is a number.
-  (assert-equal ____ (numberp 5))
-  (assert-equal ____ (numberp 2.0))
-  (assert-equal ____ (numberp "five")))
+  (assert-equal t (numberp 5))
+  (assert-equal t (numberp 2.0))
+  (assert-equal nil (numberp "five")))
 
 (define-test evaluation-order
   ;; Arguments to a function are evaluated before the function is called.
-  (assert-equal ____ (* (+ 1 2) (- 13 10))))
+    (assert-equal 9 (* (+ 1 2) (- 13 10))))
 
 (define-test basic-comparisons
   ;; The below functions are boolean functions (predicates) that operate on
   ;; numbers.
-  (assert-equal ____ (> 25 4))
-  (assert-equal ____ (< 8 2))
-  (assert-equal ____ (= 3 3))
-  (assert-equal ____ (<= 6 (/ 12 2)))
-  (assert-equal ____ (>= 20 (+ 1 2 3 4 5)))
-  (assert-equal ____ (/= 15 (+ 4 10))))
+  (assert-equal t (> 25 4))
+  (assert-equal nil (< 8 2))
+  (assert-equal t (= 3 3))
+  (assert-equal t (<= 6 (/ 12 2)))
+  (assert-equal t (>= 20 (+ 1 2 3 4 5)))
+  (assert-equal t (/= 15 (+ 4 10))))
 
 (define-test quote
   ;; Preceding a list with a quote (') will tell Lisp not to evaluate a list.
@@ -50,17 +50,17 @@
   ;; the literal list.
   ;; Evaluating the form (+ 1 2) returns the number 3, but evaluating the form
   ;; '(+ 1 2) returns the list (+ 1 2).
-  (assert-equal ____ (+ 1 2))
-  (assert-equal ____ '(+ 1 2))
-  (assert-equal ____ (list '+ 1 2))
+  (assert-equal 3 (+ 1 2))
+  (assert-equal '(+ 1 2) '(+ 1 2))
+  (assert-equal '(+ 1 2) (list '+ 1 2))
   ;; The 'X syntax is syntactic sugar for (QUOTE X).
-  (true-or-false? ____ (equal '(/ 4 0) (quote (/ 4 0)))))
+  (true-or-false? t (equal '(/ 4 0) (quote (/ 4 0)))))
 
 (define-test listp
   ;; LISTP is a predicate which returns true if the argument is a list.
-  (assert-equal ____ (listp '(1 2 3)))
-  (assert-equal ____ (listp 100))
-  (assert-equal ____ (listp "Hello world"))
-  (assert-equal ____ (listp nil))
-  (assert-equal ____ (listp (+ 1 2)))
-  (assert-equal ____ (listp '(+ 1 2))))
+  (assert-equal t (listp '(1 2 3)))
+  (assert-equal nil (listp 100))
+  (assert-equal nil (listp "Hello world"))
+  (assert-equal t (listp nil))
+  (assert-equal nil (listp (+ 1 2)))
+  (assert-equal t (listp '(+ 1 2))))

lisp-koans/koans/let.lisp

@@ -17,14 +17,14 @@
   ;; created: a symbol that names a variable becomes bound to a value.
   (let ((x 10)
         (y 20))
-    (assert-equal ____ (+ x y))
+    (assert-equal 30 (+ x y))
     ;; It is possible to shadow previously visible bindings.
     (let ((y 30))
-      (assert-equal ____ (+ x y)))
-    (assert-equal ____ (+ x y)))
+      (assert-equal 40 (+ x y)))
+    (assert-equal 30 (+ x y)))
   ;; Variables bound by LET have a default value of NIL.
   (let (x)
-    (assert-equal ____ x)))
+    (assert-equal nil x)))
 
 (define-test let-versus-let*
   ;; LET* is similar to LET, except the bindings are established sequentially,
@@ -33,30 +33,30 @@
         (y 20))
     (let ((x (+ y 100))
           (y (+ x 100)))
-      (assert-equal ____ x)
-      (assert-equal ____ y))
+      (assert-equal 120 x)
+      (assert-equal 110 y))
     (let* ((x (+ y 100))
            (y (+ x 100)))
       ;; Which X is used to compute the value of Y?
-      (assert-equal ____ x)
-      (assert-equal ____ y))))
+      (assert-equal 120 x)
+      (assert-equal 220 y))))
 
 (define-test let-it-be-equal
   ;; Fill in the LET and LET* to get the tests to pass.
   (let ((a 1)
         (b :two)
         (c "Three"))
-    (let ((____ ____)
-          (____ ____)
-          (____ ____))
+    (let ((a 100)
+          (b (* 200 a))
+          (c "Jellyfish"))
       (assert-equal a 100)
       (assert-equal b 200)
       (assert-equal c "Jellyfish"))
-    (let* ((____ ____)
-           (____ ____)
+    (let* ((a 121)
+           (b (+ a 79))
            ;; In this third binding, you are allowed to use the variables bound
            ;; by the previous two LET* bindings.
-           (____ ____))
+           (c (+ a (/ b a))))
       (assert-equal a 121)
       (assert-equal b 200)
       (assert-equal c (+ a (/ b a))))))

lisp-koans/koans/nil-false-empty.lisp

@@ -14,39 +14,39 @@
 
 (define-test t-and-nil-are-opposites
   ;; NOT is a function which returns the boolean opposite of its argument.
-  (true-or-false? ____ (not nil))
-  (true-or-false? ____ (not t)))
+  (true-or-false? t (not nil))
+  (true-or-false? nil (not t)))
 
 (define-test nil-and-empty-list-are-the-same-thing
   ;; In Common Lisp, NIL is also the empty list.
-  (true-or-false? ____ '())
-  (true-or-false? ____ (not '())))
+  (true-or-false? NIL '())
+  (true-or-false? t (not '())))
 
 (define-test in-lisp-many-things-are-true
   ;; In Common Lisp, the canonical values for truth is T.
   ;; However, everything that is non-NIL is true, too.
-  (true-or-false? ____ 5)
-  (true-or-false? ____ (not 5))
-  (true-or-false? ____ "a string")
+  (true-or-false? t 5)
+  (true-or-false? nil (not 5))
+  (true-or-false? t "a string")
   ;; Even an empty string...
-  (true-or-false? ____ "")
+  (true-or-false? t "")
   ;; ...or a list containing a NIL...
-  (true-or-false? ____ (list nil))
+  (true-or-false? t (list nil))
   ;; ...or an array with no elements...
-  (true-or-false? ____ (make-array 0))
+  (true-or-false? t (make-array 0))
   ;; ...or the number zero.
-  (true-or-false? ____ 0))
+  (true-or-false? t 0))
 
 (define-test and
   ;; The logical operator AND can take multiple arguments.
-  (true-or-false? ____ (and t t t t t))
-  (true-or-false? ____ (and t t nil t t))
+  (true-or-false? t (and t t t t t))
+  (true-or-false? nil (and t t nil t t))
   ;; If all values passed to AND are true, it returns the last value.
-  (assert-equal ____ (and t t t t t 5)))
+  (assert-equal 5 (and t t t t t 5)))
 
 (define-test or
   ;; The logical operator OR can also take multiple arguments.
-  (true-or-false? ____  (or nil nil nil t nil))
+  (true-or-false? t  (or nil nil nil t nil))
   ;; OR returns the first non-NIL value it encounters, or NIL if there are none.
-  (assert-equal ____ (or nil nil nil))
-  (assert-equal ____ (or 1 2 3 4 5)))
+  (assert-equal nil (or nil nil nil))
+  (assert-equal 1 (or 1 2 3 4 5)))

lisp-koans/koans/scope-and-extent.lisp

@@ -13,7 +13,7 @@
 ;;; limitations under the License.
 
 (define-test shadowing
-  (assert-equal ____ (let ((z 4)) (list z (let ((z 2)) z)))))
+    (assert-equal '(4 2) (let ((z 4)) (list z (let ((z 2)) z)))))
 
 (defun block-1 ()
   (block here
@@ -28,19 +28,19 @@
     (return-from outer 'valve)))
 
 (define-test block-return-from
-  (assert-equal ____ (block-1))
-  (assert-equal ____ (block-2)))
+  (assert-equal 4 (block-1))
+  (assert-equal 'space (block-2)))
 
 ;;; See http://www.gigamonkeys.com/book/variables.html
 
 (define-test lexical-variables-can-be-enclosed
-  (assert-equal ____ (let ((f (let ((x 10))
+  (assert-equal 10 (let ((f (let ((x 10))
                                 (lambda () x))))
                        (let ((x 20))
                          (funcall f)))))
 
 (define-test dynamic-variables-are-affected-by-execution-path
-  (assert-equal ____ (let ((f (let ((x 10))
+  (assert-equal 20 (let ((f (let ((x 10))
                                 (declare (special x))
                                 (lambda () x))))
                        (let ((x 20))