Add simple random functions (#402)

* Add simple random functions

* Add tests

* Formatting

* Ignore linting

Author: chrisrink10

src/basilisp/core.lpy

@@ -1651,6 +1651,40 @@
             {}
             maps)))
 
+;;;;;;;;;;;;;;;;;;;;;;
+;; Random Functions ;;
+;;;;;;;;;;;;;;;;;;;;;;
+
+(import* random)
+
+(defn rand
+  "Return a random real number between lower (default: 0) and upper (default: 1) inclusive."
+  ([] (random/uniform 0 1))
+  ([upper] (random/uniform 0 upper))
+  ([lower upper] (random/uniform lower upper)))
+
+(defn rand-int
+  "Return a random integer between lower (default: 0) and upper inclusive."
+  ([upper]
+   (random/randrange 0 upper))
+  ([lower upper]
+   (random/randrange lower upper)))
+
+(defn rand-nth
+  "Return a random element from coll."
+  [coll]
+  (nth coll (rand-int (count coll))))
+
+(defn random-sample
+  "Return elements from coll with the random probability of prob."
+  [prob coll]
+  (filter (fn [_] (< (rand) prob)) coll))
+
+(defn shuffle
+  "Return a random permutation of coll."
+  [coll]
+  (vec (random/sample (python/list coll) (count coll))))
+
 ;;;;;;;;;;;;;;;;;;;;
 ;; Utility Macros ;;
 ;;;;;;;;;;;;;;;;;;;;

src/basilisp/lang/list.py

@@ -90,7 +90,7 @@ def list(members, meta=None) -> List:  # pylint:disable=redefined-builtin
     )
 
 
-def l(*members, meta=None) -> List:
+def l(*members, meta=None) -> List:  # noqa
     """Creates a new list from members."""
     return List(  # pylint: disable=abstract-class-instantiated
         plist(iterable=members), meta=meta

tests/basilisp/core_test.py

@@ -1228,6 +1228,57 @@ def test_not_is_not_any(self, coll):
         assert True is core.not_any__Q__(core.odd__Q__, coll)
 
 
+class TestRandom:
+    COLLS = [
+        vec.v("a", "b", "c"),
+        llist.l("a", "b", "c"),
+        lset.s("a", "b", "c"),
+        ["a", "b", "c"],
+        ("a", "b", "c"),
+        {"a", "b", "c"},
+    ]
+
+    @pytest.fixture(scope="class", params=COLLS)
+    def coll(self, request):
+        return request.param
+
+    def test_rand_no_arg(self):
+        x = core.rand()
+        assert isinstance(x, float)
+        assert 0 <= x <= 1
+
+    def test_rand_only_upper(self):
+        x = core.rand(100)
+        assert isinstance(x, float)
+        assert 0 <= x <= 100
+
+    def test_rand_upper_and_lower(self):
+        x = core.rand(10, 100)
+        assert isinstance(x, float)
+        assert 10 <= x <= 100
+
+    def test_rand_int_only_upper(self):
+        i = core.rand_int(100)
+        assert isinstance(i, int)
+        assert 0 <= i <= 100
+
+    def test_rand_int_upper_and_lower(self):
+        i = core.rand_int(10, 100)
+        assert isinstance(i, int)
+        assert 10 <= i <= 100
+
+    def test_rand_nth(self, coll):
+        e = core.rand_nth(coll)
+        assert e in set(coll)
+
+    def test_random_sample(self, coll):
+        coll_elems = set(coll)
+        assert all(e in coll_elems for e in core.random_sample(0.5, coll))
+
+    def test_shuffle(self, coll):
+        assert set(coll) == set(core.shuffle(coll))
+
+
 def test_merge():
     assert None is core.merge()
     assert lmap.Map.empty() == core.merge(lmap.Map.empty())