Merge pull request #1772 from Kodiologist/py38

Support Python 3.8

.travis.yml

@@ -6,6 +6,7 @@ python:
   - "3.5"
   - "3.6"
   - "3.7"
+  - 3.8-dev
   - pypy2.7-6.0
   - pypy3.5-6.0
 install:

NEWS.rst

@@ -9,8 +9,10 @@ Removals
 
 New Features
 ------------------------------
+* Python 3.8 is now supported.
 * Format strings with embedded Hy code (e.g., `f"The sum is {(+ x y)}"`)
   are now supported, even on Pythons earlier than 3.6.
+* Added a special form `setx` to create Python 3.8 assignment expressions.
 * New list? function.
 * New tuple? function.
 

conftest.py

@@ -4,7 +4,7 @@ import importlib
 import py
 import pytest
 import hy
-from hy._compat import PY3, PY36
+from hy._compat import PY3, PY36, PY38
 
 NATIVE_TESTS = os.path.join("", "tests", "native_tests", "")
 
@@ -13,7 +13,8 @@ _fspath_pyimport = py.path.local.pyimport
 
 def pytest_ignore_collect(path, config):
     return (("py3_only" in path.basename and not PY3) or
-            ("py36_only" in path.basename and not PY36) or None)
+            ("py36_only" in path.basename and not PY36) or
+            ("py38_only" in path.basename and not PY38) or None)
 
 
 def pyimport_patch_mismatch(self, **kwargs):

docs/conf.py

@@ -2,7 +2,7 @@
 #
 # This file is execfile()d with the current directory set to its containing dir.
 
-import re, os, sys, time, cgi
+import re, os, sys, time, html
 sys.path.append(os.path.abspath(".."))
 
 extensions = ['sphinx.ext.intersphinx']
@@ -28,7 +28,7 @@ copyright = u'%s the authors' % time.strftime('%Y')
 version = ".".join(hy_version.split(".")[:-1])
 # The full version, including alpha/beta/rc tags.
 release = hy_version
-hy_descriptive_version = cgi.escape(hy_version)
+hy_descriptive_version = html.escape(hy_version)
 if "+" in hy_version:
     hy_descriptive_version += " <strong style='color: red;'>(unstable)</strong>"
 

docs/language/api.rst

@@ -412,6 +412,21 @@ They can be used to assign multiple variables at once:
     =>
 
 
+``setv`` always returns ``None``.
+
+
+setx
+-----
+
+Whereas ``setv`` creates an assignment statement, ``setx`` creates an assignment expression (see :pep:`572`). It requires Python 3.8 or later. Only one target–value pair is allowed, and the target must be a bare symbol, but the ``setx`` form returns the assigned value instead of ``None``.
+
+::
+
+    => (when (> (setx x (+ 1 2)) 0)
+    ...  (print x "is greater than 0"))
+    3 is greater than 0
+
+
 defclass
 --------
 

hy/_compat.py

@@ -11,6 +11,7 @@ import sys, keyword, textwrap
 PY3 = sys.version_info[0] >= 3
 PY36 = sys.version_info >= (3, 6)
 PY37 = sys.version_info >= (3, 7)
+PY38 = sys.version_info >= (3, 8)
 
 # The value of UCS4 indicates whether Unicode strings are stored as UCS-4.
 # It is always true on Pythons >= 3.3, which use USC-4 on all systems.

hy/cmdline.py

@@ -270,8 +270,9 @@ class HyREPL(code.InteractiveConsole, object):
             try:
                 # Mush the two AST chunks into a single module for
                 # conversion into Python.
-                new_ast = ast.Module(exec_ast.body +
-                                     [ast.Expr(eval_ast.body)])
+                new_ast = ast.Module(
+                    exec_ast.body + [ast.Expr(eval_ast.body)],
+                    type_ignores=[])
                 print(astor.to_source(new_ast))
             except Exception:
                 msg = 'Exception in AST callback:\n{}\n'.format(

hy/compiler.py

@@ -15,7 +15,7 @@ from hy.errors import (HyCompileError, HyTypeError, HyLanguageError,
 from hy.lex import mangle, unmangle, hy_parse, parse_one_thing, LexException
 
 from hy._compat import (string_types, str_type, bytes_type, long_type, PY3,
-                        PY36, reraise)
+                        PY36, PY38, reraise)
 from hy.macros import require, load_macros, macroexpand, tag_macroexpand
 
 import hy.core
@@ -1399,15 +1399,16 @@ class HyASTCompiler(object):
             expr, target=target, value=ret.force_expr, op=op())
 
     @special("setv", [many(FORM + FORM)])
+    @special((PY38, "setx"), [times(1, 1, SYM + FORM)])
     def compile_def_expression(self, expr, root, pairs):
         if not pairs:
             return asty.Name(expr, id='None', ctx=ast.Load())
         result = Result()
         for pair in pairs:
-            result += self._compile_assign(*pair)
+            result += self._compile_assign(root, *pair)
         return result
 
-    def _compile_assign(self, name, result):
+    def _compile_assign(self, root, name, result):
 
         str_name = "%s" % name
         if str_name in (["None"] + (["True", "False"] if PY3 else [])):
@@ -1427,14 +1428,18 @@ class HyASTCompiler(object):
                 and isinstance(name, HySymbol)
                 and '.' not in name):
             result.rename(name)
-            # Throw away .expr to ensure that (setv ...) returns None.
-            result.expr = None
+            if root != HySymbol("setx"):
+                # Throw away .expr to ensure that (setv ...) returns None.
+                result.expr = None
         else:
             st_name = self._storeize(name, ld_name)
-            result += asty.Assign(
+            node = (asty.NamedExpr
+                if root == HySymbol("setx")
+                else asty.Assign)
+            result += node(
                 name if hasattr(name, "start_line") else result,
-                targets=[st_name],
-                value=result.force_expr)
+                value=result.force_expr,
+                target=st_name, targets=[st_name])
 
         return result
 
@@ -2131,7 +2136,7 @@ def hy_compile(tree, module, root=ast.Module, get_expr=False,
                    key=lambda a: not (isinstance(a, ast.ImportFrom) and
                                       a.module == '__future__'))
 
-    ret = root(body=body)
+    ret = root(body=body, type_ignores=[])
 
     if get_expr:
         expr = ast.Expression(body=expr)

setup.cfg

@@ -22,3 +22,4 @@ python_functions=test_* is_test_* hyx_test_* hyx_is_test_*
 filterwarnings =
     once::DeprecationWarning
     once::PendingDeprecationWarning
+    ignore::SyntaxWarning

setup.py

@@ -31,7 +31,11 @@ class Install(install):
                         "." + filename[:-len(".hy")])
         install.run(self)
 
-install_requires = ['rply>=0.7.7', 'astor>=0.7.1', 'funcparserlib>=0.3.6', 'clint>=0.4']
+install_requires = [
+    'rply>=0.7.7',
+    'astor @ https://github.com/berkerpeksag/astor/archive/master.zip',
+    'funcparserlib>=0.3.6',
+    'clint>=0.4']
 if os.name == 'nt':
     install_requires.append('pyreadline>=2.1')
 
@@ -79,6 +83,7 @@ setup(
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
         "Topic :: Software Development :: Code Generators",
         "Topic :: Software Development :: Compilers",
         "Topic :: Software Development :: Libraries",

tests/native_tests/language.hy

@@ -11,7 +11,7 @@
         pytest)
 (import sys)
 
-(import [hy._compat [PY3 PY37]])
+(import [hy._compat [PY3 PY37 PY38]])
 
 (defn test-sys-argv []
   "NATIVE: test sys.argv"
@@ -1550,10 +1550,11 @@ cee\"} dee" "ey bee\ncee dee"))
 (defn test-disassemble []
   "NATIVE: Test the disassemble function"
   (assert (= (disassemble '(do (leaky) (leaky) (macros))) (cond
-    [PY3 "Module(
+    [PY3 (.format "Module(
     body=[Expr(value=Call(func=Name(id='leaky'), args=[], keywords=[])),
         Expr(value=Call(func=Name(id='leaky'), args=[], keywords=[])),
-        Expr(value=Call(func=Name(id='macros'), args=[], keywords=[]))])"]
+        Expr(value=Call(func=Name(id='macros'), args=[], keywords=[]))]{})"
+      (if PY38 ",\n    type_ignores=[]" ""))]
     [True "Module(
     body=[
         Expr(value=Call(func=Name(id='leaky'), args=[], keywords=[], starargs=None, kwargs=None)),

tests/native_tests/py38_only_tests.hy

@@ -0,0 +1,29 @@
+;; Copyright 2019 the authors.
+;; This file is part of Hy, which is free software licensed under the Expat
+;; license. See the LICENSE.
+
+;; Tests where the emitted code relies on Python ≥3.8.
+;; conftest.py skips this file when running on Python <3.8.
+
+(import pytest)
+
+(defn test-setx []
+  (setx y (+ (setx x (+ "a" "b")) "c"))
+  (assert (= x "ab"))
+  (assert (= y "abc"))
+
+  (setv l [])
+  (for [x [1 2 3]]
+    (when (>= (setx y (+ x 8)) 10)
+      (.append l y)))
+  (assert (= l [10 11]))
+
+  (setv a ["apple" None "banana"])
+  (setv filtered (lfor
+    i (range (len a))
+    :if (is-not (setx v (get a i)) None)
+    v))
+  (assert (= filtered ["apple" "banana"]))
+  (assert (= v "banana"))
+  (with [(pytest.raises NameError)]
+    i))