March 2014 update

Task/Ackermann-function/D/ackermann-function-2.d

@@ -3,8 +3,7 @@ import std.stdio, std.bigint, std.conv;
 BigInt ipow(BigInt base, BigInt exp) pure /*nothrow*/ {
     auto result = 1.BigInt;
     while (exp) {
-        //if (exp & 1)
-        if (exp % 2)
+        if (exp & 1)
             result *= base;
         exp >>= 1;
         base *= base;

Task/Ackermann-function/Perl-6/ackermann-function-1.pl6

@@ -1,7 +1,5 @@
 sub A(Int $m, Int $n) {
-
-	$m == 0  ??    $n + 1                   !!
-	$n == 0  ??  A($m - 1, 1            )   !!
-	             A($m - 1, A($m, $n - 1));
-
+    if    $m == 0 { $n + 1 }
+    elsif $n == 0 { A($m - 1, 1) }
+    else          { A($m - 1, A($m, $n - 1)) }
 }

Task/Ackermann-function/Rust/ackermann-function.rust

@@ -0,0 +1,15 @@
+ // works for Rust 0.9
+fn main() {
+	let a: int = ack(3, 4); // 125
+	println!("{}", a.to_str());
+}
+
+fn ack(m: int, n: int) -> int {
+	if m == 0 {
+		n + 1
+	} else if n == 0 {
+		ack(m - 1, 1)
+	} else {
+		ack(m - 1, ack(m, n - 1))
+	}
+}

Task/Ackermann-function/TXR/ackermann-function.txr

@@ -0,0 +1,23 @@
+@(do
+   (defmacro defmemofun (name (. args) . body)
+     (let ((hash (gensym "hash-"))
+           (argl (gensym "args-"))
+           (hent (gensym "hent-"))
+           (uniq (copy-str "uniq")))
+       ^(let ((,hash (hash :equal-based)))
+          (defun ,name (,*args)
+            (let* ((,argl (list ,*args))
+                   (,hent (inhash ,hash ,argl ,uniq)))
+              (if (eq (cdr ,hent) ,uniq)
+                (set (cdr ,hent) (block ,name (progn ,*body)))
+                (cdr ,hent)))))))
+
+   (defmemofun ack (m n)
+     (cond
+       ((= m 0) (+ n 1))
+       ((= n 0) (ack (- m 1) 1))
+       (t (ack (- m 1) (ack m (- n 1))))))
+
+   (each ((i (range 0 3)))
+     (each ((j (range 0 4)))
+        (format t "ack(~a, ~a) = ~a\n" i j (ack i j)))))