Re: Instead of pcase

[Ihor Radchenko]

Richard Stallman <rms@gnu.org> writes:

>   > > I wonder why people defined `xor'.  It can't be used
>   > > as a conditional, like `and' and `or', so what is the point of it?
>
>   > `xor' can be used as conditional
>
> Perhaps we are miscommunicating.
>
> `or' and `and' can act as conditionals.  (and X Y) says to
> do Y if X is true.  (or X Y) says to do Y if X is false.
> That is why those constructs are useful.

IMHO, it is a better practice to do code flow control via special forms
like `if', `when', `prog1', `progn', etc.

In my mind, `or' and `and' are to be used as function (they are, indeed,
functions). Treating them as flow control constructs may lead to
confusion, as it did for you.

> `xor' can'e be used as a conditional, because all of the arguments of
> `xor' must always be evaluatedd.

`xor' is a function - in cond*, PRED may be any function. And the fact
that not all the arguments are evaluated in (PRED x arg1 arg2 ...) is
the source of my confusion and the reason why I objected the idea of
PRED in its current form when "x" not visually distinct from the rest of
the arguments.

-- 
Ihor Radchenko // yantar92,
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