A-M baby

Task/Forward-difference/D/forward-difference-1.d

@@ -0,0 +1,20 @@
+import std.stdio;
+
+T[] forwardDifference(T)(in T[] data, in int level) pure nothrow
+    in {
+        assert(level >= 0 && level < data.length);
+    } body {
+        //auto result = data.dup; // not nothrow
+        auto result = data ~ []; // slower
+        foreach (i; 0 .. level)
+            foreach (j, ref el; result[0 .. $ - i - 1])
+                el = result[j + 1] - el;
+        result.length -= level;
+        return result;
+    }
+
+void main() {
+    auto data = [90.5, 47, 58, 29, 22, 32, 55, 5, 55, 73.5];
+    foreach (level; 0 .. data.length)
+        writeln(forwardDifference(data, level));
+}