Merge master onto pr/471

Conflicts:
	hy/core/language.hy
This commit is contained in:
Abhishek L 2014-01-30 21:50:23 +05:30
commit 4b54e3c748
14 changed files with 464 additions and 10 deletions

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@ -29,6 +29,48 @@ Returns true if argument is iterable and not a string.
False
cons
----
.. versionadded:: 0.9.13
Usage: ``(cons a b)``
Returns a fresh :ref:`cons cell <hycons>` with car `a` and cdr `b`.
.. code-block:: clojure
=> (setv a (cons 'hd 'tl))
=> (= 'hd (car a))
True
=> (= 'tl (cdr a))
True
cons?
-----
.. versionadded:: 0.9.13
Usage: ``(cons? foo)``
Checks whether ``foo`` is a :ref:`cons cell <hycons>`.
.. code-block:: clojure
=> (setv a (cons 'hd 'tl))
=> (cons? a)
True
=> (cons? nil)
False
=> (cons? [1 2 3])
False
.. _dec-fn:
dec
@ -284,6 +326,28 @@ Contrast with :ref:`iterable?-fn`.
=> (iterator? (iter {:a 1 :b 2 :c 3}))
True
list*
-----
Usage: ``(list* head &rest tail)``
Generate a chain of nested cons cells (a dotted list) containing the
arguments. If the argument list only has one element, return it.
.. code-block:: clojure
=> (list* 1 2 3 4)
(1 2 3 . 4)
=> (list* 1 2 3 [4])
[1, 2, 3, 4]
=> (list* 1)
1
=> (cons? (list* 1 2 3 4))
True
.. _macroexpand-fn:
macroexpand
@ -863,5 +927,3 @@ Return an iterator from ``coll`` as long as predicate, ``pred`` returns True.
=> (list (take-while neg? [ 1 2 3 -4 5]))
[]

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@ -172,6 +172,38 @@ keywords, that is keywords used by the language definition inside
function signatures. Lambda-list keywords are symbols starting with a
``&``. The class inherits :ref:`HyString`
.. _hycons:
Cons Cells
==========
``hy.models.cons.HyCons`` is a representation of Python-friendly `cons
cells`_. Cons cells are especially useful to mimic features of "usual"
LISP variants such as Scheme or Common Lisp.
.. _cons cells: http://en.wikipedia.org/wiki/Cons
A cons cell is a 2-item object, containing a ``car`` (head) and a
``cdr`` (tail). In some Lisp variants, the cons cell is the fundamental
building block, and S-expressions are actually represented as linked
lists of cons cells. This is not the case in Hy, as the usual
expressions are made of Python lists wrapped in a
``HyExpression``. However, the ``HyCons`` mimicks the behavior of
"usual" Lisp variants thusly:
- ``(cons something nil)`` is ``(HyExpression [something])``
- ``(cons something some-list)`` is ``((type some-list) (+ [something]
some-list))`` (if ``some-list`` inherits from ``list``).
- ``(get (cons a b) 0)`` is ``a``
- ``(slice (cons a b) 1)`` is ``b``
Hy supports a dotted-list syntax, where ``'(a . b)`` means ``(cons 'a
'b)`` and ``'(a b . c)`` means ``(cons 'a (cons 'b 'c))``. If the
compiler encounters a cons cell at the top level, it raises a
compilation error.
``HyCons`` wraps the passed arguments (car and cdr) in Hy types, to ease
the manipulation of cons cells in a macro context.
Hy Internal Theory
==================

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@ -32,6 +32,7 @@ from hy.models.symbol import HySymbol # NOQA
from hy.models.float import HyFloat # NOQA
from hy.models.dict import HyDict # NOQA
from hy.models.list import HyList # NOQA
from hy.models.cons import HyCons # NOQA
import hy.importer # NOQA

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@ -34,6 +34,7 @@ from hy.models.symbol import HySymbol
from hy.models.float import HyFloat
from hy.models.list import HyList
from hy.models.dict import HyDict
from hy.models.cons import HyCons
from hy.errors import HyCompileError, HyTypeError
@ -597,6 +598,24 @@ class HyASTCompiler(object):
return imports, HyExpression([HySymbol(name),
contents]).replace(form), False
elif isinstance(form, HyCons):
ret = HyExpression([HySymbol(name)])
nimport, contents, splice = self._render_quoted_form(form.car,
level)
if splice:
raise HyTypeError(form, "Can't splice dotted lists yet")
imports.update(nimport)
ret.append(contents)
nimport, contents, splice = self._render_quoted_form(form.cdr,
level)
if splice:
raise HyTypeError(form, "Can't splice the cdr of a cons")
imports.update(nimport)
ret.append(contents)
return imports, ret.replace(form), False
elif isinstance(form, (HySymbol, HyLambdaListKeyword)):
return imports, HyExpression([HySymbol(name),
HyString(form)]).replace(form), False
@ -1645,15 +1664,15 @@ class HyASTCompiler(object):
@builds(HyExpression)
def compile_expression(self, expression):
if expression == []:
return self.compile_list(expression)
# Perform macro expansions
expression = macroexpand(expression, self.module_name)
if not isinstance(expression, HyExpression):
# Go through compile again if the type changed.
return self.compile(expression)
if expression == []:
return self.compile_list(expression)
fn = expression[0]
func = None
if isinstance(fn, HyKeyword):
@ -2036,6 +2055,10 @@ class HyASTCompiler(object):
self.module_name)
return Result()
@builds(HyCons)
def compile_cons(self, cons):
raise HyTypeError(cons, "Can't compile a top-level cons cell")
@builds(HyInteger)
def compile_integer(self, number):
return ast.Num(n=long_type(number),

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@ -25,6 +25,8 @@
(import [hy._compat [long-type]]) ; long for python2, int for python3
(import [hy.models.cons [HyCons]])
(defn _numeric-check [x]
(if (not (numeric? x))
@ -34,6 +36,14 @@
"Checks whether item is a collection"
(and (iterable? coll) (not (string? coll))))
(defn cons [a b]
"Return a fresh cons cell with car = a and cdr = b"
(HyCons a b))
(defn cons? [c]
"Check whether c can be used as a cons object"
(instance? HyCons c))
(defn cycle [coll]
"Yield an infinite repetition of the items in coll"
(setv seen [])
@ -200,6 +210,12 @@
(try (= x (iter x))
(catch [TypeError] false)))
(defn list* [hd &rest tl]
"Return a dotted list construed from the elements of the argument"
(if (not tl)
hd
(cons hd (apply list* tl))))
(defn macroexpand [form]
"Return the full macro expansion of form"
(import hy.macros)
@ -321,11 +337,10 @@
(_numeric_check n)
(= n 0))
(def *exports* '[calling-module-name coll? cycle dec distinct
(def *exports* '[calling-module-name coll? cons cons? cycle dec distinct
disassemble drop drop-while empty? even? first filter
flatten float? gensym identity inc instance? integer
integer? integer-char? iterable? iterate iterator?
macroexpand macroexpand-1 neg? nil? none? nth
numeric? odd? pos? remove repeat repeatedly rest
second string string? take take-nth take-while
zero?])
list* macroexpand macroexpand-1 neg? nil? none? nth
numeric? odd? pos? remove repeat repeatedly rest second
string string? take take-nth take-while zero?])

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@ -24,6 +24,7 @@ from functools import wraps
from rply import ParserGenerator
from hy.models.complex import HyComplex
from hy.models.cons import HyCons
from hy.models.dict import HyDict
from hy.models.expression import HyExpression
from hy.models.float import HyFloat
@ -95,9 +96,40 @@ def real_main_empty(p):
return []
def reject_spurious_dots(*items):
"Reject the spurious dots from items"
for list in items:
for tok in list:
if tok == "." and type(tok) == HySymbol:
raise LexException("Malformed dotted list",
tok.start_line, tok.start_column)
@pg.production("paren : LPAREN list_contents RPAREN")
@set_boundaries
def paren(p):
cont = p[1]
# Dotted lists are expressions of the form
# (a b c . d)
# that evaluate to nested cons cells of the form
# (a . (b . (c . d)))
if len(cont) >= 3 and isinstance(cont[-2], HySymbol) and cont[-2] == ".":
reject_spurious_dots(cont[:-2], cont[-1:])
if len(cont) == 3:
# Two-item dotted list: return the cons cell directly
return HyCons(cont[0], cont[2])
else:
# Return a nested cons cell
return HyCons(cont[0], paren([p[0], cont[1:], p[2]]))
# Warn preemptively on a malformed dotted list.
# Only check for dots after the first item to allow for a potential
# attribute accessor shorthand
reject_spurious_dots(cont[1:])
return HyExpression(p[1])

108
hy/models/cons.py Normal file
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@ -0,0 +1,108 @@
# Copyright (c) 2013 Nicolas Dandrimont <nicolas.dandrimont@crans.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
from hy.macros import _wrap_value
from hy.models import HyObject
from hy.models.expression import HyExpression
from hy.models.symbol import HySymbol
class HyCons(HyObject):
"""
HyCons: a cons object.
Building a HyCons of something and a HyList really builds a HyList
"""
__slots__ = ["car", "cdr"]
def __new__(cls, car, cdr):
if isinstance(cdr, list):
# Keep unquotes in the cdr of conses
if type(cdr) == HyExpression:
if len(cdr) > 0 and type(cdr[0]) == HySymbol:
if cdr[0] in ("unquote", "unquote_splice"):
return super(HyCons, cls).__new__(cls)
return cdr.__class__([_wrap_value(car)] + cdr)
elif cdr is None:
return HyExpression([_wrap_value(car)])
else:
return super(HyCons, cls).__new__(cls)
def __init__(self, car, cdr):
self.car = _wrap_value(car)
self.cdr = _wrap_value(cdr)
def __getitem__(self, n):
if n == 0:
return self.car
if n == slice(1, None):
return self.cdr
raise IndexError(
"Can only get the car ([0]) or the cdr ([1:]) of a HyCons")
def __setitem__(self, n, new):
if n == 0:
self.car = new
return
if n == slice(1, None):
self.cdr = new
return
raise IndexError(
"Can only set the car ([0]) or the cdr ([1:]) of a HyCons")
def __iter__(self):
yield self.car
try:
iterator = (i for i in self.cdr)
except TypeError:
if self.cdr is not None:
yield self.cdr
raise TypeError("Iteration on malformed cons")
else:
for i in iterator:
yield i
def replace(self, other):
if self.car is not None:
self.car.replace(other)
if self.cdr is not None:
self.cdr.replace(other)
HyObject.replace(self, other)
def __repr__(self):
if isinstance(self.cdr, self.__class__):
return "(%s %s)" % (repr(self.car), repr(self.cdr)[1:-1])
else:
return "(%s . %s)" % (repr(self.car), repr(self.cdr))
def __eq__(self, other):
return (
isinstance(other, self.__class__) and
self.car == other.car and
self.cdr == other.cdr
)

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@ -36,5 +36,16 @@ class HyList(HyObject, list):
def __add__(self, other):
return self.__class__(super(HyList, self).__add__(other))
def __getslice__(self, start, end):
return self.__class__(super(HyList, self).__getslice__(start, end))
def __getitem__(self, item):
ret = super(HyList, self).__getitem__(item)
if isinstance(item, slice):
return self.__class__(ret)
return ret
def __repr__(self):
return "[%s]" % (" ".join([repr(x) for x in self]))

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@ -2,6 +2,7 @@
import hy # noqa
from .native_tests.cons import * # noqa
from .native_tests.defclass import * # noqa
from .native_tests.math import * # noqa
from .native_tests.native_macros import * # noqa

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@ -475,3 +475,8 @@ def test_attribute_access():
cant_compile("(. foo bar :baz [0] quux [frob])")
cant_compile("(. foo bar baz (0) quux [frob])")
cant_compile("(. foo bar baz [0] quux {frob})")
def test_cons_correct():
"""Ensure cons gets compiled correctly"""
can_compile("(cons a b)")

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@ -1,4 +1,5 @@
# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
# Copyright (c) 2014 Nicolas Dandrimont <nicolas.dandrimont@crans.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
@ -26,6 +27,8 @@ from hy.models.complex import HyComplex
from hy.models.symbol import HySymbol
from hy.models.string import HyString
from hy.models.dict import HyDict
from hy.models.list import HyList
from hy.models.cons import HyCons
from hy.lex import LexException, PrematureEndOfInput, tokenize
@ -302,3 +305,32 @@ def test_lex_mangling_qmark():
assert entry == [HySymbol("is_foo.bar")]
entry = tokenize(".foo?.bar.baz?")
assert entry == [HySymbol(".is_foo.bar.is_baz")]
def test_simple_cons():
"""Check that cons gets tokenized correctly"""
entry = tokenize("(a . b)")[0]
assert entry == HyCons(HySymbol("a"), HySymbol("b"))
def test_dotted_list():
"""Check that dotted lists get tokenized correctly"""
entry = tokenize("(a b c . (d . e))")[0]
assert entry == HyCons(HySymbol("a"),
HyCons(HySymbol("b"),
HyCons(HySymbol("c"),
HyCons(HySymbol("d"),
HySymbol("e")))))
def test_cons_list():
"""Check that cons of something and a list gets tokenized as a list"""
entry = tokenize("(a . [])")[0]
assert entry == HyList([HySymbol("a")])
assert type(entry) == HyList
entry = tokenize("(a . ())")[0]
assert entry == HyExpression([HySymbol("a")])
assert type(entry) == HyExpression
entry = tokenize("(a b . {})")[0]
assert entry == HyDict([HySymbol("a"), HySymbol("b")])
assert type(entry) == HyDict

56
tests/models/test_cons.py Normal file
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@ -0,0 +1,56 @@
# Copyright (c) 2013 Nicolas Dandrimont <nicolas.dandrimont@crans.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
from hy.models.cons import HyCons
def test_cons_slicing():
"""Check that cons slicing works as expected"""
cons = HyCons("car", "cdr")
assert cons[0] == "car"
assert cons[1:] == "cdr"
try:
cons[:]
assert True is False
except IndexError:
pass
try:
cons[1]
assert True is False
except IndexError:
pass
def test_cons_replacing():
"""Check that assigning to a cons works as expected"""
cons = HyCons("foo", "bar")
cons[0] = "car"
assert cons == HyCons("car", "bar")
cons[1:] = "cdr"
assert cons == HyCons("car", "cdr")
try:
cons[:] = "foo"
assert True is False
except IndexError:
pass

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@ -2,8 +2,21 @@ from hy.models.list import HyList
def test_list_add():
"""Check that adding two HyLists generates a HyList"""
a = HyList([1, 2, 3])
b = HyList([3, 4, 5])
c = a + b
assert c == [1, 2, 3, 3, 4, 5]
assert c.__class__ == HyList
def test_list_slice():
"""Check that slicing a HyList produces a HyList"""
a = HyList([1, 2, 3, 4])
sl1 = a[1:]
sl5 = a[5:]
assert type(sl1) == HyList
assert sl1 == HyList([2, 3, 4])
assert type(sl5) == HyList
assert sl5 == HyList([])

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@ -0,0 +1,63 @@
(defn test-cons-mutability []
"Test the mutability of conses"
(setv tree (cons (cons 1 2) (cons 2 3)))
(setv (car tree) "foo")
(assert (= tree (cons "foo" (cons 2 3))))
(setv (cdr tree) "bar")
(assert (= tree (cons "foo" "bar"))))
(defn test-cons-quoting []
"Test quoting of conses"
(assert (= (cons 1 2) (quote (1 . 2))))
(assert (= (quote foo) (car (quote (foo . bar)))))
(assert (= (quote bar) (cdr (quote (foo . bar))))))
(defn test-cons-behavior []
"NATIVE: test the behavior of cons is consistent"
(defn t= [a b]
(and (= a b) (= (type a) (type b))))
(assert (t= (cons 1 2) '(1 . 2)))
(assert (t= (cons 1 nil) '(1)))
(assert (t= (cons nil 2) '(nil . 2)))
(assert (t= (cons 1 []) [1]))
(setv tree (cons (cons 1 2) (cons 2 3)))
(assert (t= (car tree) (cons 1 2)))
(assert (t= (cdr tree) (cons 2 3))))
(defn test-cons-iteration []
"NATIVE: test the iteration behavior of cons"
(setv x '(0 1 2 3 4 . 5))
(setv it (iter x))
(for* [i (range 6)]
(assert (= i (next it))))
(assert
(= 'success
(try
(do
(next it)
'failurenext)
(except [e TypeError] (if (= e.args (, "Iteration on malformed cons"))
'success
'failureexc))
(except [e Exception] 'failureexc2)))))
(defn test-cons? []
"NATIVE: test behavior of cons?"
(assert (cons? (cons 1 2)))
(assert (cons? '(1 . 2)))
(assert (cons? '(1 2 3 . 4)))
(assert (cons? (list* 1 2 3)))
(assert (not (cons? (cons 1 [2]))))
(assert (not (cons? (list* 1 nil)))))
(defn test-list* []
"NATIVE: test behavior of list*"
(assert (= 1 (list* 1)))
(assert (= (cons 1 2) (list* 1 2)))
(assert (= (cons 1 (cons 2 3)) (list* 1 2 3)))
(assert (= '(1 2 3 4 . 5) (list* 1 2 3 4 5))))