std.algorithm.cacheの使用例 http://qiita.com/giiko_/items/8c3442e8e7a83cc0b91a

zoi.d

import std.algorithm;
import std.random;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

void main()
{
	immutable dic = [["今日","ぞい"],["も"],["1","ぞい"],["日","ぞい"],["がん","ぞい"],["ばる","ぞい"],["ぞい！"]];

	auto count = dic
		.map!(w => w.randomSample(1).front).repeat.map!join
		.cache
		.tee!(writeln, No.pipeOnPop).until("今日も1日がんばるぞい！")
		.walkLength + 1;

	writefln("がんばるまで %s zoiでした", count);
}