Just another update

Task/Anonymous-recursion/D/anonymous-recursion-1.d

@@ -1,14 +1,14 @@
-import std.stdio, std.exception;
+int fib(in uint arg) pure nothrow @safe @nogc {
+    assert(arg >= 0);
 
-int fib(int arg) pure {
-    enforce(arg >= 0);
-
-    return function int (int n) pure nothrow {
-        auto self = __traits(parent, {});
+    return function uint(in uint n) pure nothrow @safe @nogc {
+        static immutable self = &__traits(parent, {});
         return (n < 2) ? n : self(n - 1) + self(n - 2);
     }(arg);
 }
 
 void main() {
+    import std.stdio;
+
     39.fib.writeln;
 }