Thorsten,
Here is a problem (again!) with using a pil backquote expression,
where the user, like you or me, is stuck on "CL-unquote thinking".
Let's call g again, but now we switch the places of the dates and
times. In this case, we might expect the answer now to be "No";
however, the answer will remain "Yes".
: (g Is $S1$ before $S2$?
The answer is
`(if (and
(<= $D2$ $D1$)
(<= $T2$ $T1$) )
"Yes"
"No" ) )
-> "Is \"1999-09-09 20:12:05\" before \"2000-03-04 18:03:03\"? The
answer is \"Yes\""
Why?
Because when the backquote expression gets resolved by the reader, the
symbols $D1$, $D2$, $T1$, and $T2$ are not bound to any values
(i.e. will evaluate to NIL). And since
(<= NIL NIL)
evals to T, g will always see "Yes" as its last argument.
Sorry. That means you have to come up with another way to eval "code"
in your DSL (i.e the stuff under g).
I hope this make sense. This is what Alex has been trying to tell us
all along. (I only now just realized this; so you can see how far
I've come along: not much.)
Best, --Rick
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