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Fix documentation and add warning voice

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Jay McCarthy 2010-06-29 16:02:42 -06:00
parent 18078400b7
commit 4e932f6c6b
1 changed files with 9 additions and 1 deletions
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collects/datalog/scribblings/racket.scrbl
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@ -73,6 +73,14 @@ Statements are either assertions, retractions, or queries.
Questions are either literals or external queries.
Literals are represented as @racket[identifier] or @racket[(identifier term ...)].
Questions are represented as @racket[(identifier term ... :- term ...)], where @racket[identifier] is bound to a procedure that when given the first set of terms as arguments returns the second set of terms as values.
External queries are represented as @racket[(identifier term ... :- term ...)], where @racket[identifier] is bound to a procedure that when given the first set of terms as arguments returns the second set of terms as values.
A term is either a non-capitalized identifiers for a constant symbol, a Racket datum for a constant datum, or a capitalized identifier for a variable symbol. Bound identifiers in terms are treated as datums.
External queries invalidate Datalog's guaranteed termination. For example, this program does not terminate:
@racketblock[
(datalog (make-theory)
(! (:- (loop X)
(add1 X :- Z)
(loop Z)))
(? (loop 1)))
]