Shadow get (#1344)

NEWS

@@ -12,6 +12,7 @@ Changes from 0.13.0
      as necessary, so you can write ``(eval `(+ 1 ~n))`` instead of
      ``(eval `(+ 1 ~(HyInteger n)))``
    * Literal `Inf`s and `NaN`s must now be capitalized like that
+   * `get` is available as a function
 
    [ Bug Fixes ]
    * Numeric literals are no longer parsed as symbols when followed by a dot

hy/core/shadow.hy

@@ -138,11 +138,18 @@
 (defn not-in [x y]
   (not-in x y))
 
+(defn get [coll key1 &rest keys]
+  (setv coll (get coll key1))
+  (for* [k keys]
+    (setv coll (get coll k)))
+  coll)
+
 (setv *exports* [
   '+ '- '* '** '/ '// '% '@
   '<< '>> '& '| '^ '~
   '< '> '<= '>= '= '!=
   'and 'or 'not
-  'is 'is-not 'in 'not-in])
+  'is 'is-not 'in 'not-in
+  'get])
 (if (not PY35)
   (.remove *exports* '@))

tests/native_tests/operators.hy

@@ -288,3 +288,11 @@
   (assert (is (f 3 [1 2]) (!= f-name "in")))
   (assert (is (f 2 [1 2]) (= f-name "in")))
   (forbid (f 2 [1 2] [3 4])))
+
+
+(op-and-shadow-test [get]
+  (forbid (f))
+  (forbid (f "hello"))
+  (assert (= (f "hello" 1) "e"))
+  (assert (= (f [[1 2 3] [4 5 6] [7 8 9]] 1 2) 6))
+  (assert (= (f {"x" {"y" {"z" 12}}} "x" "y" "z") 12)))