Populate the matrix with a compute function.

prototype/Doubt/Matrix.swift

@@ -1,4 +1,19 @@
 struct Matrix<A> {
+	init(width: Int, height: Int, compute: (Int, Int) -> A) {
+		self.width = width
+		self.height = height
+		var values: [Memo<A>] = []
+		values.reserveCapacity(width * height)
+
+		for i in 0..<width {
+			for j in 0..<height {
+				values[i + j * height] = Memo<A> { compute(i, j) }
+			}
+		}
+
+		self.values = values
+	}
+
 	let width: Int
 	let height: Int