Support one-arity comparison operators too

Comparison operators such as =, !=, <, >, <=, >= should support a
one-arity version too, and return true in those cases (except for !=,
which returns false).

This closes #949.

Reported-by: Matthew Egan Odendahl
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

hy/compiler.py

@@ -1774,18 +1774,7 @@ class HyASTCompiler(object):
                               values=[value.force_expr for value in values])
         return ret
 
-    @builds("=")
-    @builds("!=")
-    @builds("<")
-    @builds("<=")
-    @builds(">")
-    @builds(">=")
-    @builds("is")
-    @builds("in")
-    @builds("is_not")
-    @builds("not_in")
-    @checkargs(min=2)
-    def compile_compare_op_expression(self, expression):
+    def _compile_compare_op_expression(self, expression):
         ops = {"=": ast.Eq, "!=": ast.NotEq,
                "<": ast.Lt, "<=": ast.LtE,
                ">": ast.Gt, ">=": ast.GtE,
@@ -1805,6 +1794,32 @@ class HyASTCompiler(object):
                                  lineno=e.start_line,
                                  col_offset=e.start_column)
 
+    @builds("=")
+    @builds("!=")
+    @builds("<")
+    @builds("<=")
+    @builds(">")
+    @builds(">=")
+    @checkargs(min=1)
+    def compile_compare_op_expression(self, expression):
+        if len(expression) == 2:
+            rval = "True"
+            if expression[0] == "!=":
+                rval = "False"
+            return ast.Name(id=rval,
+                            ctx=ast.Load(),
+                            lineno=expression.start_line,
+                            col_offset=expression.start_column)
+        return self._compile_compare_op_expression(expression)
+
+    @builds("is")
+    @builds("in")
+    @builds("is_not")
+    @builds("not_in")
+    @checkargs(min=2)
+    def compile_compare_op_expression_coll(self, expression):
+        return self._compile_compare_op_expression(expression)
+
     @builds("%")
     @builds("**")
     @builds("<<")

tests/compilers/test_ast.py

@@ -468,9 +468,9 @@ def test_ast_unicode_strings():
 def test_compile_error():
     """Ensure we get compile error in tricky cases"""
     try:
-        can_compile("(fn [] (= 1))")
+        can_compile("(fn [] (in [1 2 3]))")
     except HyTypeError as e:
-        assert(e.message == "`=' needs at least 2 arguments, got 1.")
+        assert(e.message == "`in' needs at least 2 arguments, got 1.")
     else:
         assert(False)
 

tests/native_tests/language.hy

@@ -208,15 +208,26 @@
 
 (defn test-noteq []
   "NATIVE: not eq"
-  (assert (!= 2 3)))
+  (assert (!= 2 3))
+  (assert (not (!= 1))))
+
+
+(defn test-eq []
+  "NATIVE: eq"
+  (assert (= 1 1))
+  (assert (= 1)))
 
 
 (defn test-numops []
   "NATIVE: test numpos"
   (assert (> 5 4 3 2 1))
+  (assert (> 1))
   (assert (< 1 2 3 4 5))
+  (assert (< 1))
   (assert (<= 5 5 5 5 ))
-  (assert (>= 5 5 5 5 )))
+  (assert (<= 1))
+  (assert (>= 5 5 5 5 ))
+  (assert (>= 1)))
 
 
 (defn test-is []