Allow more than two arguments to `in` or `not-in`

NEWS.rst

@@ -33,6 +33,7 @@ Bug Fixes
 ------------------------------
 * Statements in the second argument of `assert` are now executed.
 * Fixed the expression of a while loop that contains statements being compiled twice.
+* `in` and `not-in` now allow more than two arguments, as in Python.
 * `hy2py` can now handle format strings.
 * Fixed crashes from inaccessible history files.
 * The unit tests no longer unintentionally import the internal Python module "test".

hy/compiler.py

@@ -1270,8 +1270,7 @@ class HyASTCompiler(object):
         return self._c_ops[k]()
 
     @special(["=", "is", "<", "<=", ">", ">="], [oneplus(FORM)])
-    @special(["!=", "is-not"], [times(2, Inf, FORM)])
-    @special(["in", "not-in"], [times(2, 2, FORM)])
+    @special(["!=", "is-not", "in", "not-in"], [times(2, Inf, FORM)])
     def compile_compare_op_expression(self, expr, root, args):
         if len(args) == 1:
             return (self.compile(args[0]) +

hy/core/shadow.hy

@@ -117,6 +117,12 @@
 (defn is-not [a1 a2 &rest a-rest]
   "Shadowed `is-not` keyword perform is-not on `a1` by `a2`, ..., `a-rest`."
   (comp-op operator.is-not a1 (+ (, a2) a-rest)))
+(defn in [a1 a2 &rest a-rest]
+  "Shadowed `in` keyword perform `a1` in `a2` in …."
+  (comp-op (fn [x y] (in x y)) a1 (+ (, a2) a-rest)))
+(defn not-in [a1 a2 &rest a-rest]
+  "Shadowed `not in` keyword perform `a1` not in `a2` not in…."
+  (comp-op (fn [x y] (not-in x y)) a1 (+ (, a2) a-rest)))
 (defn >= [a1 &rest a-rest]
   "Shadowed `>=` operator perform ge comparison on `a1` by each `a-rest`."
   (comp-op operator.ge a1 a-rest))
@@ -148,14 +154,6 @@
   "Shadowed `not` keyword perform not on `x`."
   (not x))
 
-(defn in [x y]
-  "Shadowed `in` keyword perform `x` in `y`."
-  (in x y))
-
-(defn not-in [x y]
-  "Shadowed `not in` keyword perform `x` not in `y`."
-  (not-in x y))
-
 (defn get [coll key1 &rest keys]
   "Access item in `coll` indexed by `key1`, with optional `keys` nested-access."
   (setv coll (get coll key1))

tests/native_tests/operators.hy

@@ -294,7 +294,8 @@
   (forbid (f 3))
   (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])))
+  (assert (is (f 2 [1 2] [[1 2] 3]) (= f-name "in")))
+  (assert (is (f 3 [1 2] [[2 2] 3]) (!= f-name "in"))))
 
 
 (op-and-shadow-test [get]