update

Task/Pascals-triangle/00DESCRIPTION

@@ -6,3 +6,6 @@
 where each element of each row is either 1 or the sum of the two elements right above it. For example, the next row would be 1 (since the first element of each row doesn't have two elements above it), 4 (1 + 3), 6 (3 + 3), 4 (3 + 1), and 1 (since the last element of each row doesn't have two elements above it). Each row <tt>n</tt> (starting with row 0 at the top) shows the coefficients of the binomial expansion of (x + y)<sup>n</sup>.
 
 Write a function that prints out the first n rows of the triangle (with <tt>f(1)</tt> yielding the row consisting of only the element 1). This can be done either by summing elements from the previous rows or using a binary coefficient or combination function. Behavior for <tt>n <= 0</tt> does not need to be uniform, but should be noted.
+
+'''See also:'''
+* [[Evaluate binomial coefficients]]

Task/Pascals-triangle/D/pascals-triangle-2.d

@@ -1,12 +1,11 @@
 import std.stdio, std.algorithm, std.range;
 
-auto pascal(in int n) /*pure nothrow*/ {
-   auto p = [[1]];
-   foreach (_; 1 .. n)
-      p ~= zip(p[$-1] ~ 0, 0 ~ p[$-1]).map!q{a[0] + a[1]}().array();
-   return p;
+auto pascal() /*pure nothrow*/ {
+    return [1].recurrence!q{ zip(a[n - 1] ~ 0, 0 ~ a[n - 1])
+                             .map!q{a[0] + a[1]}
+                             .array };
 }
 
 void main() {
-    writeln(pascal(5));
+    pascal.take(5).writeln;
 }