tasks a-s

Task/Parametric-polymorphism/Go/parametric-polymorphism.go

@@ -0,0 +1,53 @@
+package main
+
+import "fmt"
+
+func average(c intCollection) float64 {
+    var sum, count int
+    c.mapElements(func(n int) {
+        sum += n
+        count++
+    })
+    return float64(sum) / float64(count)
+}
+
+func main() {
+    t1 := new(binaryTree)
+    t2 := new(bTree)
+    a1 := average(t1)
+    a2 := average(t2)
+    fmt.Println("binary tree average:", a1)
+    fmt.Println("b-tree average:", a2)
+}
+
+type intCollection interface {
+    mapElements(func(int))
+}
+
+type binaryTree struct {
+    // dummy representation details
+    left, right bool
+}
+
+func (t *binaryTree) mapElements(visit func(int)) {
+    // dummy implementation
+    if t.left == t.right {
+        visit(3)
+        visit(1)
+        visit(4)
+    }
+}
+
+type bTree struct {
+    // dummy representation details
+    buckets int
+}
+
+func (t *bTree) mapElements(visit func(int)) {
+    // dummy implementation
+    if t.buckets >= 0 {
+        visit(1)
+        visit(5)
+        visit(9)
+    }
+}