I'm curios if it is possible (and if so how should one implement) something like
string-containso
in core.logic.
an example usage would be something like
(db-rel person x)
(def database
(db
[person "John"]
[person "Jane"]
[person "Jim"]
[person "Dan"]
[person "Bob"]))
(with-db database
(run* [q]
(string-containso q "o")))
;would return ("John" "Bob")
Thanks in advance,
Boogie
If you know the substring you're searching for, you can use pred, which is handy for lifting any predicate into core.logic:
(defn string-containso
[string substring]
(pred string #(.contains % substring)))
(with-db database
(run* [q]
(person q)
(string-containso q "o")))
; => (John Bob)
It's a little more interesting if you also want to be able to search for substrings. You could try enumerating all of a string's substrings and checking whether that includes a given one:
(defn substrings
[s]
(for [start (range (inc .length s))
end (range (inc start) (inc (.length s)))]
(.substring s start end)))
(defn string-containso
[string substring]
(fresh [all-substrings]
(is all-substrings string substrings)
(membero substring all-substrings)))
Now, you can still use this the way you did before:
(with-db database
(run* [q]
(person q)
(string-containso q "o")))
; => (John Bob)
But you could also use it to get all of the substrings:
(with-db database
(run* [q]
(fresh [p]
(person p)
(string-containso p q))))
; => (J Jo J Joh John Ji o J oh Jim ohn h i hn Ja n im D m Jan B Jane Da a Bo an Dan ane Bob n a ne o e an ob n b)
