<div class="gmail_quote">On Sun, Feb 19, 2012 at 17:03, Hendrik Boom <<a href="mailto:hendrik@topoi.pooq.com">hendrik@topoi.pooq.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div class="im"> </div>The trouble is, I can never remember which of 'nand' and 'nor' is which. Either of them could mean 'neither'. But I do know what 'neither' means. </blockquote><div> Think of them as composed boolean functions: - nand is "not and" - nor is "not or" `and' is true only when both (all) arguments are true. False otherwise. `nand' is false only when both (all) arguments are true. True otherwise. Truth table: A B (nand A B) t t f t f t f t t f f t `or' is false only when both (all) arguments are false. True otherwise. `nor' is true only when both (all) arguments are false. True otherwise. </div></div>A B (nor A B) t t f t f f f t f f f t So, when you say 'neither' you mean 'nor'. Ah, then there's also XOR (eXclusive OR): True when the arguments are different. A B (xor A B) t t f t f t f t t f f f Anyway, IMHO I don't see need to have these bindings in #lang racket.