Merge branch 'master' into pr/468

docs/language/api.rst

@@ -352,6 +352,8 @@ below:
     Meow
 
 
+.. _defn:
+
 defn / defun
 ------------
 
@@ -422,6 +424,29 @@ Parameters may have following keywords in front of them:
         => (zig-zag-sum 1 2 3 4 5 6)
         -3
 
+.. _defn-alias / defun-alias:
+
+defn-alias / defun-alias
+------------------------
+
+.. versionadded:: 0.9.13
+
+The `defn-alias` and `defun-alias` macros are much like `defn`_ above,
+with the difference that instead of defining a function with a single
+name, these can also define aliases. Other than taking a list of
+symbols for function names as the first parameter, `defn-alias` and
+`defun-alias` have no other differences compared to `defn` and
+`defun`.
+
+.. code-block:: clj
+
+  => (defn-alias [main-name alias] []
+  ...  (print "Hello!"))
+  => (main-name)
+  "Hello!"
+  => (alias)
+  "Hello!"
+
 .. _defmacro:
 
 defmacro
@@ -679,13 +704,16 @@ would thrown a `NameError`.
     (set-a 5)
     (print-a)
 
-if
---
+if / if-not
+-----------
 
 the `if` form is used to conditionally select code to be executed. It has to
 contain the condition block and the block to be executed if the condition
 evaluates `True`. Optionally it may contain a block that is executed in case
-the evaluation of the condition is `False`.
+the evaluation of the condition is `False`. The `if-not` form (*new in
+0.9.13*) is similar, but the first block after the test will be
+executed when the test fails, while the other, conditional one, when
+the test succeeds - opposite of the order of the `if` form.
 
 Example usage:
 
@@ -695,6 +723,10 @@ Example usage:
       (print "lets go shopping")
       (print "lets go and work"))
 
+    (if-not (money-left? account)
+      (print "lets go and work")
+      (print "lets go shopping"))
+
 Truth values of Python objects are respected. Values `None`, `False`, zero of
 any numeric type, empty sequence and empty dictionary are considered `False`.
 Everything else is considered `True`.

hy/core/macros.hy

@@ -138,6 +138,13 @@
   ret)
 
 
+(defmacro if-not [test not-branch &optional [yes-branch nil]]
+  "Like `if`, but execute the first branch when the test fails"
+  (if (nil? yes-branch)
+    `(if (not ~test) ~not-branch)
+    `(if (not ~test) ~not-branch ~yes-branch)))
+
+
 (defmacro when [test &rest body]
   "Execute `body` when `test` is true"
   `(if ~test (do ~@body)))
@@ -145,7 +152,7 @@
 
 (defmacro unless [test &rest body]
   "Execute `body` when `test` is false"
-  `(if ~test None (do ~@body)))
+  `(if-not ~test (do ~@body)))
 
 
 (defmacro yield-from [iterable]
@@ -181,3 +188,14 @@
       (setv -args (cdr (car -args))))
 
     `(apply ~-fun [~@-args] (dict (sum ~-okwargs [])))))
+
+
+(defmacro-alias [defn-alias defun-alias] [names lambda-list &rest body]
+  "define one function with several names"
+  (let [[main (first names)]
+        [aliases (rest names)]]
+    (setv ret `(do (defn ~main ~lambda-list ~@body)))
+    (for* [name aliases]
+          (.append ret
+                   `(setv ~name ~main)))
+    ret))

tests/native_tests/native_macros.hy

@@ -176,3 +176,22 @@
   (assert (in ":res_" s1))
   (assert (in ":res_" s2))
   (assert (not (= s1 s2))))
+
+
+(defn test-if-not []
+  (assert (= (if-not True :yes :no)
+             :no))
+  (assert (= (if-not False :yes :no)
+             :yes))
+  (assert (nil? (if-not True :yes)))
+  (assert (= (if-not False :yes)
+             :yes)))
+
+
+(defn test-defn-alias []
+  (defn-alias [tda-main tda-a1 tda-a2] [] :bazinga)
+  (defun-alias [tda-main tda-a1 tda-a2] [] :bazinga)
+  (assert (= (tda-main) :bazinga))
+  (assert (= (tda-a1) :bazinga))
+  (assert (= (tda-a2) :bazinga))
+  (assert (= tda-main tda-a1 tda-a2)))