Add zero- and one-argument versions of 'and' and 'or' (ref. #824)

hy/compiler.py

@@ -1631,15 +1631,22 @@ def compile_require(self, expression):
 
     @builds("and")
     @builds("or")
-    @checkargs(min=2)
     def compile_logical_or_and_and_operator(self, expression):
-        ops = {"and": ast.And,
-               "or": ast.Or}
+        ops = {"and": (ast.And, "True"),
+               "or": (ast.Or, "False")}
         operator = expression.pop(0)
+        opnode, default = ops[operator]
+        root_line, root_column = operator.start_line, operator.start_column
+        if len(expression) == 0:
+            return ast.Name(id=default,
+                            ctx=ast.Load(),
+                            lineno=root_line,
+                            col_offset=root_column)
+        elif len(expression) == 1:
+            return self.compile(expression[0])
         ret = Result()
         values = list(map(self.compile, expression))
         has_stmt = any(value.stmts for value in values)
-        root_line, root_column = operator.start_line, operator.start_column
         if has_stmt:
             # Compile it to an if...else sequence
             var = self.get_anon_var()
@@ -1692,7 +1699,7 @@ def make_assign(value, node=None):
             ret = sum(root, ret)
             ret += Result(expr=expr_name, temp_variables=[expr_name, name])
         else:
-            ret += ast.BoolOp(op=ops[operator](),
+            ret += ast.BoolOp(op=opnode(),
                               lineno=root_line,
                               col_offset=root_column,
                               values=[value.force_expr for value in values])

tests/native_tests/language.hy

@@ -759,9 +759,13 @@
 (defn test-and []
   "NATIVE: test the and function"
   (let [[and123 (and 1 2 3)]
-        [and-false (and 1 False 3)]]
+        [and-false (and 1 False 3)]
+        [and-true (and)]
+        [and-single (and 1)]]
     (assert (= and123 3))
-    (assert (= and-false False)))
+    (assert (= and-false False))
+    (assert (= and-true True))
+    (assert (= and-single 1)))
   ; short circuiting
   (setv a 1)
   (and 0 (setv a 2))
@@ -772,10 +776,14 @@
   "NATIVE: test the or function"
   (let [[or-all-true (or 1 2 3 True "string")]
         [or-some-true (or False "hello")]
-        [or-none-true (or False False)]]
+        [or-none-true (or False False)]
+        [or-false (or)]
+        [or-single (or 1)]]
     (assert (= or-all-true 1))
     (assert (= or-some-true "hello"))
-    (assert (= or-none-true False)))
+    (assert (= or-none-true False))
+    (assert (= or-false False))
+    (assert (= or-single 1)))
   ; short circuiting
   (setv a 1)
   (or 1 (setv a 2))