Add all the A tasks

Task/Anonymous-recursion/Go/anonymous-recursion.go

@@ -0,0 +1,47 @@
+package main
+
+import "fmt"
+
+func main() {
+    for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 40, -1} {
+        f, ok := arFib(n)
+        if ok {
+            fmt.Printf("fib %d = %d\n", n, f)
+        } else {
+            fmt.Println("fib undefined for negative numbers")
+        }
+    }
+}
+
+func arFib(n int) (int, bool) {
+    switch {
+    case n < 0:
+        return 0, false
+    case n < 2:
+        return n, true
+    }
+    return yc(func(recurse fn) fn {
+        return func(left, term1, term2 int) int {
+            if left == 0 {
+                return term1+term2
+            }
+            return recurse(left-1, term1+term2, term1)
+        }
+    })(n-2, 1, 0), true
+}
+
+type fn func(int, int, int) int
+type ff func(fn) fn
+type fx func(fx) fn
+
+func yc(f ff) fn {
+    return func(x fx) fn {
+        return f(func(a1, a2, a3 int) int {
+            return x(x)(a1, a2, a3)
+        })
+    }(func(x fx) fn {
+        return f(func(a1, a2, a3 int) int {
+            return x(x)(a1, a2, a3)
+        })
+    })
+}