&gt; In many other languages, every programmer can write their own &quot;even&quot; and &quot;filter&quot; with their own idiosyncrasy.<p>&quot;filter&quot; is incredibly useful, and most modern languages (including Java 8) have it built in.<p>&quot;even?&quot; is sometimes useful, and languages are kind of hit-and-miss about it, but its usually small enough to inline, and the biggest cost of not having it built-in is probably things like people using modulus rather than first-bit testing in Java which, IIRC, produces somewhat slower code for that check.