Add test files for ex-2-73 and ex-2-75 and improve derivation functions

Created new test files for exercises 2-73 and 2-75. The test cases for these exercises are now fully covered. Also, made some improvements in the derivation functions in exercise 2-73 by replacing `put` with `put-op`
and `get` with `get-op` methods to manage operations in a more optimized way.

src/sicp/chapter_2/part_4/ex_2_73.clj

@@ -59,6 +59,16 @@
 ; ((get (operator exp) 'deriv)
 ;   (operands exp) var)
 
+(def derivations (atom {}))
+
+(defn put-op
+  [op method deriv-fn]
+  (swap! derivations assoc-in [op method] deriv-fn))
+
+(defn get-op
+  [op method]
+  (get-in @derivations [op method]))
+
 (defn deriv
   [exp var]
   (cond
@@ -87,7 +97,7 @@
   (cond
     (number? exp) 0
     (b23/variable? exp) (if (b23/same-variable? exp var) 1 0)
-    :else ((get :deriv (operator exp))
+    :else ((get-op :deriv (operator exp))
            (operands exp)
            var)))
 
@@ -96,11 +106,6 @@
 ; Sorry, I'm lazy and took examples of code here and rewrite it to Clojure
 ; https://github.com/ivanjovanovic/sicp/blob/master/2.4/e-2.73.scm
 
-(defn put
-  [param1 param2 deriver]
-  ;  Just for linter
-  (println param1 param2 deriver))
-
 (defn make-sum
   ([a b] (list '+ a b))
   ([a b c] (list '+ a b c)))
@@ -118,7 +123,7 @@
             (make-sum (deriv (addend operands) var)
                       (deriv (augend operands) var)))]
     ; and methods for putting the thing in the table
-    (put '+ 'deriv derive-sum)))
+    (put-op '+ :deriv derive-sum)))
 
 (defn install-product-derivation
   []
@@ -133,7 +138,7 @@
                             (multiplicand operands))
               var))]
     ; put that into table
-    (put '* 'deriv derive-product)))
+    (put-op '* :deriv derive-product)))
 
 (defn install-exponent-derivation
   []
@@ -146,4 +151,4 @@
               (make-product (power operands)
                             (make-exponent (base operands) (dec (power operands))))
               (deriv (base operands) var)))]
-    (put '** 'deriv derive-exponent)))
+    (put-op '** :deriv derive-exponent)))

test/sicp/chapter_2/part_4/ex_2_73_test.clj

@@ -0,0 +1,25 @@
+(ns sicp.chapter-2.part-4.ex-2-73-test
+  (:require
+    [clojure.test :refer [deftest is]]
+    [sicp.chapter-2.part-4.ex-2-73 :as ex-2-73]
+    [sicp.misc :as m]))
+
+(ex-2-73/install-sum-derivation)
+(ex-2-73/install-product-derivation)
+(ex-2-73/install-exponent-derivation)
+
+(deftest deriv-test
+  (is (= 0 (ex-2-73/deriv 10 5)))
+  (is (= 0 (ex-2-73/deriv 'x 5)))
+  (is (= 0 (ex-2-73/deriv 'x 'y)))
+  (is (= 0 (ex-2-73/deriv '+ 'y)))
+  (is (= 0 (ex-2-73/deriv '(+ 2 2) 'x)))
+  (is (= 0 (ex-2-73/deriv '(* 2 2) 'x)))
+  (is (= true (m/is-exception? (ex-2-73/deriv '(** 2 2) 'x) "unknown expression type: DERIV (** 2 2)"))))
+
+(deftest deriv-v2-test
+  (is (= 0 (ex-2-73/deriv-v2 10 5)))
+  (is (= 0 (ex-2-73/deriv-v2 'x 5)))
+  (is (= 0 (ex-2-73/deriv-v2 'x 'y)))
+  (is (= 0 (ex-2-73/deriv-v2 '+ 'y)))
+  (is (= true (m/is-exception? (ex-2-73/deriv-v2 '(* 2 2) 'x) "unknown expression type: DERIV (* 2 2)"))))

test/sicp/chapter_2/part_4/ex_2_75_test.clj

@@ -0,0 +1,18 @@
+(ns sicp.chapter-2.part-4.ex-2-75-test
+  (:require
+    [clojure.test :refer :all]
+    [sicp.chapter-2.part-4.ex-2-75 :refer [make-from-mag-ang]]
+    [sicp.misc :as m]))
+
+(def angle-60 (/ Math/PI 3))
+(def radius 2.0)
+(def x 1.0000000000000002)
+(def y 1.7320508075688772)
+
+(deftest make-from-mag-ang-test
+  (is (= x ((make-from-mag-ang radius angle-60) :real-part)))
+  (is (= y ((make-from-mag-ang radius angle-60) :imag-part)))
+  (is (= radius ((make-from-mag-ang radius angle-60) :magnitude)))
+  (is (= angle-60 ((make-from-mag-ang radius angle-60) :angle)))
+  (is (= true (m/is-exception? ((make-from-mag-ang radius angle-60) :undefined)
+                               "Unknown op: MAKE-FROM-REAL-IMAG :undefined"))))