Document namespaced clojure function requirement

[jessie-ross]

I haven't used Datomic, but I have been following it's documentation to learn Datascript, I believe have found this gap in the behaviour between Datomic and Datascript queries, it would be good to document it:

• Allow calling clojure.core functions in queries #424

[tonsky]

This is not exactly true. These functions don’t need to be qualified:

datascript/src/datascript/built_ins.cljc

Lines 81 to 99 in 8c01d1b

	(def query-fns
	{'= =, '== ==, 'not= not=, '!= not=,
	'< less, '> greater, '<= less-equal, '>= greater-equal,
	'+ +, '- -, '* *, '/ /,
	'quot quot, 'rem rem, 'mod mod, 'inc inc, 'dec dec, 'max max, 'min min,
	'zero? zero?, 'pos? pos?, 'neg? neg?, 'even? even?, 'odd? odd?, 'compare compare,
	'rand rand, 'rand-int rand-int,
	'true? true?, 'false? false?, 'nil? nil?, 'some? some?, 'not not, 'and and-fn, 'or or-fn,
	'complement complement, 'identical? identical?,
	'identity identity, 'keyword keyword, 'meta meta, 'name name, 'namespace namespace, 'type type,
	'vector vector, 'list list, 'set set, 'hash-map hash-map, 'array-map array-map,
	'count count, 'range range, 'not-empty not-empty, 'empty? empty?, 'contains? contains?,
	'str str, 'subs, subs, 'get get,
	'pr-str pr-str, 'print-str print-str, 'println-str println-str, 'prn-str prn-str,
	're-find re-find, 're-matches re-matches, 're-seq re-seq, 're-pattern re-pattern,
	'-differ? -differ?, 'get-else -get-else, 'get-some -get-some, 'missing? -missing?, 'ground identity,
	'clojure.string/blank? str/blank?, 'clojure.string/includes? str/includes?,
	'clojure.string/starts-with? str/starts-with?, 'clojure.string/ends-with? str/ends-with?
	'tuple vector, 'untuple identity})

For custom functions, in CLJS even fully-qualified won’t work. You’ll have to pass fn as an argument.

Finally, Datomic seems to require fully-qualified too:

[jessie-ross]

Finally, Datomic seems to require fully-qualified too:

Ah I wasn't clear enough perhaps, I mean clojure.core functions, see this example:

(require '[datomic.api :as d :refer [q db]])

(def uri "datomic:dev://localhost:4334/mbrainz-1968-1973")
(def conn (d/connect uri))
(def the-db (d/db conn))


;; Check I am running this correctly:
(d/q '[:find ?artist-name .
       :in $
       :where
       [?a :artist/name   ?artist-name]
       [?t :track/artists ?a]
       [?t :track/name    "Baby's Heartbeat"]]
     the-db) ;; => "John Lennon"

;; clojure.core/concat is included
(d/q '[:find ?result .
       :in $ ?a ?b
       :where
       [(concat ?a ?b) ?result]]
     the-db ["a"] ["b"]) ;; => ("a" "b")

;; Checking if it includes symbols present in the current namespace
(defn foo [a] (str a "-foo"))

;; It doesn't
(d/q '[:find ?result .
       :in $ ?a
       :where
       [(foo ?a) ?result]]
     the-db "a") ;; => Unable to resolve foo in this context

(d/q '[:find ?result .
       :in $ ?a
       :where
       [(user/foo ?a) ?result]]
     the-db "a") ;; => "a-foo"

I was following this blog post and tripped over the difference between datomic and datascript on functions like concat, and butlast. I am not sure whether just Datomic has a larger amount of functions allowed or whether it includes clojure.core.

Now that I've solved the issue it isn't of great importance to me, but I was thinking it might be nice to document it.

[jessie-ross]

Happened across some further official docs in the Datomic Query Reference:

Datomic provides the following built-in expression functions and predicates:

• [...]
• All of the functions from the clojure.core namespace of Clojure, except eval.
• [...]

https://docs.datomic.com/query/query-data-reference-only.html#built-in-functions

Function names outside clojure.core need to be fully qualified and included on the classpath for Pro, or in the ion :allow list for Cloud.

https://docs.datomic.com/query/query-data-reference-only.html#calling-clojure-functions

[tonsky]

Do you want to update the PR?