Add get to built-ins for binding on map values

src/datascript/built_ins.cljc

@@ -78,9 +78,9 @@
      false)))
 
 (def query-fns {
-  '= =, '== ==, 'not= not=, '!= not=, 
-  '< less, '> greater, '<= less-equal, '>= greater-equal, 
-  '+ +, '- -, '* *, '/ /, 
+  '= =, '== ==, '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,
@@ -89,7 +89,8 @@
   '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, 'pr-str pr-str, 'print-str print-str, 'println-str println-str, 'prn-str prn-str, 'subs subs,
+  '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?,
@@ -180,7 +181,7 @@
    'distinct set
    'min      aggregate-min
    'max      aggregate-max
-   'rand     aggregate-rand              
+   'rand     aggregate-rand
    'sample   aggregate-sample
    'count    count
    'count-distinct aggregate-count-distinct})

test/datascript/test/query.cljc

@@ -230,6 +230,14 @@
               "X")
          #{["abcX"] ["aXb"]})))
 
+(deftest test-built-in-get
+  (is (= (d/q '[:find ?m ?m-value
+                :in [[?k ?m] ...] ?m-key
+                :where [(get ?m ?m-key) ?m-value]]
+              {:a {:b 1}
+               :c {:d 2}}
+              :d)
+         #{[{:d 2} 2]})))
 
 (deftest ^{:doc "issue-385"} test-join-unrelated
   (is (= #{}