# [racket] Boolean expressions [Was: static variables question]

On Sun, Feb 19, 2012 at 17:03, Hendrik Boom <hendrik at topoi.pooq.com> wrote:
>*
*>* 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.
*>*
*>*
*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.
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.
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