Don't let HyExpression etc. inherit from HyList

This means the compiler no longer allows e.g. `(fn (x) ...)` in place of `(fn [x] ...)`.

NEWS.rst

@@ -12,6 +12,10 @@ Removals
 
 Other Breaking Changes
 ------------------------------
+* `HyExpression`, `HyDict`, and `HySet` no longer inherit from `HyList`.
+  This means you can no longer use alternative punctuation in place of
+  square brackets in special forms (e.g. `(fn (x) ...)` instead of
+  the standard `(fn [x] ...)`).
 * Mangling rules have been overhauled, such that mangled names
   are always legal Python identifiers
 * `_` and `-` are now equivalent even as single-character names

docs/language/internals.rst

@@ -48,26 +48,35 @@ Hy also attempts to color pretty reprs using ``clint.textui.colored``.
 This module has a flag to disable coloring,
 and a method ``clean`` to strip colored strings of their color tags.
 
+.. _hysequence:
+
+HySequence
+~~~~~~~~~~
+
+``hy.models.HySequence`` is the abstract base class of "iterable" Hy
+models, such as HyExpression and HyList.
+
+Adding a HySequence to another iterable object reuses the class of the
+left-hand-side object, a useful behavior when you want to concatenate Hy
+objects in a macro, for instance.
+
+
 .. _hylist:
 
 HyList
-~~~~~~
+~~~~~~~~~~~~
 
-``hy.models.HyList`` is the base class of "iterable" Hy models. Its
+``hy.models.HyExpression`` is a :ref:`HySequence` for bracketed ``[]``
-basic use is to represent bracketed ``[]`` lists, which, when used as a
+lists, which, when used as a top-level expression, translate to Python
-top-level expression, translate to Python list literals in the
+list literals in the compilation phase.
-compilation phase.
 
-Adding a HyList to another iterable object reuses the class of the
-left-hand-side object, a useful behavior when you want to concatenate Hy
-objects in a macro, for instance.
 
 .. _hyexpression:
 
 HyExpression
 ~~~~~~~~~~~~
 
-``hy.models.HyExpression`` inherits :ref:`HyList` for
+``hy.models.HyExpression`` inherits :ref:`HySequence` for
 parenthesized ``()`` expressions. The compilation result of those
 expressions depends on the first element of the list: the compiler
 dispatches expressions between compiler special-forms, user-defined
@@ -78,8 +87,8 @@ macros, and regular Python function calls.
 HyDict
 ~~~~~~
 
-``hy.models.HyDict`` inherits :ref:`HyList` for curly-bracketed ``{}``
+``hy.models.HyDict`` inherits :ref:`HySequence` for curly-bracketed
-expressions, which compile down to a Python dictionary literal.
+``{}`` expressions, which compile down to a Python dictionary literal.
 
 The decision of using a list instead of a dict as the base class for
 ``HyDict`` allows easier manipulation of dicts in macros, with the added

hy/compiler.py

@@ -5,7 +5,7 @@
 
 from hy.models import (HyObject, HyExpression, HyKeyword, HyInteger, HyComplex,
                        HyString, HyBytes, HySymbol, HyFloat, HyList, HySet,
-                       HyDict, wrap_value)
+                       HyDict, HySequence, wrap_value)
 from hy.errors import HyCompileError, HyTypeError
 
 from hy.lex.parser import mangle
@@ -670,7 +670,7 @@ class HyASTCompiler(object):
         name = form.__class__.__name__
         imports = set([name])
 
-        if isinstance(form, (HyList, HyDict, HySet)):
+        if isinstance(form, HySequence):
             if not form:
                 contents = HyList()
             else:

hy/models.py

@@ -233,9 +233,9 @@ class HyComplex(HyObject, complex):
 _wrappers[complex] = HyComplex
 
 
-class HyList(HyObject, list):
+class HySequence(HyObject, list):
     """
-    Hy List. Basically just a list.
+    An abstract type for sequence-like models to inherit from.
     """
 
     def replace(self, other):
@@ -246,23 +246,23 @@ class HyList(HyObject, list):
         return self
 
     def __add__(self, other):
-        return self.__class__(super(HyList, self).__add__(other))
+        return self.__class__(super(HySequence, self).__add__(other))
 
     def __getslice__(self, start, end):
-        return self.__class__(super(HyList, self).__getslice__(start, end))
+        return self.__class__(super(HySequence, self).__getslice__(start, end))
 
     def __getitem__(self, item):
-        ret = super(HyList, self).__getitem__(item)
+        ret = super(HySequence, self).__getitem__(item)
 
         if isinstance(item, slice):
             return self.__class__(ret)
 
         return ret
 
-    color = staticmethod(colored.cyan)
+    color = None
 
     def __repr__(self):
-        return str(self) if PRETTY else super(HyList, self).__repr__()
+        return str(self) if PRETTY else super(HySequence, self).__repr__()
 
     def __str__(self):
         with pretty():
@@ -276,11 +276,15 @@ class HyList(HyObject, list):
             else:
                 return '' + c(self.__class__.__name__ + "()")
 
+
+class HyList(HySequence):
+    color = staticmethod(colored.cyan)
+
 _wrappers[list] = lambda l: HyList(wrap_value(x) for x in l)
 _wrappers[tuple] = lambda t: HyList(wrap_value(x) for x in t)
 
 
-class HyDict(HyList):
+class HyDict(HySequence):
     """
     HyDict (just a representation of a dict)
     """
@@ -316,7 +320,7 @@ class HyDict(HyList):
 _wrappers[dict] = lambda d: HyDict(wrap_value(x) for x in sum(d.items(), ()))
 
 
-class HyExpression(HyList):
+class HyExpression(HySequence):
     """
     Hy S-Expression. Basically just a list.
     """
@@ -327,7 +331,7 @@ _wrappers[Fraction] = lambda e: HyExpression(
     [HySymbol("fraction"), wrap_value(e.numerator), wrap_value(e.denominator)])
 
 
-class HySet(HyList):
+class HySet(HySequence):
     """
     Hy set (just a representation of a set)
     """

tests/compilers/test_ast.py

@@ -241,6 +241,9 @@ def test_ast_good_lambda():
 def test_ast_bad_lambda():
     "Make sure AST can't compile invalid lambda"
     cant_compile("(fn)")
+    cant_compile("(fn ())")
+    cant_compile("(fn () 1)")
+    cant_compile("(fn (x) 1)")
 
 
 def test_ast_good_yield():
@@ -381,11 +384,11 @@ def test_ast_expression_basics():
 
 def test_ast_anon_fns_basics():
     """ Ensure anon fns work. """
-    code = can_compile("(fn (x) (* x x))").body[0].value
+    code = can_compile("(fn [x] (* x x))").body[0].value
     assert type(code) == ast.Lambda
-    code = can_compile("(fn (x) (print \"multiform\") (* x x))").body[0]
+    code = can_compile("(fn [x] (print \"multiform\") (* x x))").body[0]
     assert type(code) == ast.FunctionDef
-    can_compile("(fn (x))")
+    can_compile("(fn [x])")
     cant_compile("(fn)")
 
 
@@ -420,16 +423,16 @@ def test_argument_destructuring():
 
 def test_lambda_list_keywords_rest():
     """ Ensure we can compile functions with lambda list keywords."""
-    can_compile("(fn (x &rest xs) (print xs))")
+    can_compile("(fn [x &rest xs] (print xs))")
-    cant_compile("(fn (x &rest xs &rest ys) (print xs))")
+    cant_compile("(fn [x &rest xs &rest ys] (print xs))")
-    can_compile("(fn (&optional a &rest xs) (print xs))")
+    can_compile("(fn [&optional a &rest xs] (print xs))")
 
 
 def test_lambda_list_keywords_kwargs():
     """ Ensure we can compile functions with &kwargs."""
-    can_compile("(fn (x &kwargs kw) (list x kw))")
+    can_compile("(fn [x &kwargs kw] (list x kw))")
-    cant_compile("(fn (x &kwargs xs &kwargs ys) (list x xs ys))")
+    cant_compile("(fn [x &kwargs xs &kwargs ys] (list x xs ys))")
-    can_compile("(fn (&optional x &kwargs kw) (list x kw))")
+    can_compile("(fn [&optional x &kwargs kw] (list x kw))")
 
 
 def test_lambda_list_keywords_kwonly():
@@ -452,8 +455,8 @@ def test_lambda_list_keywords_kwonly():
 
 def test_lambda_list_keywords_mixed():
     """ Ensure we can mix them up."""
-    can_compile("(fn (x &rest xs &kwargs kw) (list x xs kw))")
+    can_compile("(fn [x &rest xs &kwargs kw] (list x xs kw))")
-    cant_compile("(fn (x &rest xs &fasfkey {bar \"baz\"}))")
+    cant_compile("(fn [x &rest xs &fasfkey {bar \"baz\"}])")
     if PY3:
         can_compile("(fn [x &rest xs &kwargs kwxs &kwonly kwoxs]"
                     "  (list x xs kwxs kwoxs))")

tests/importer/test_importer.py

@@ -84,5 +84,5 @@ def test_eval():
     assert eval_str('(.strip " fooooo   ")') == 'fooooo'
     assert eval_str(
         '(if True "this is if true" "this is if false")') == "this is if true"
-    assert eval_str('(list-comp (pow num 2) (num (range 100)) (= (% num 2) 1))') == [
+    assert eval_str('(list-comp (pow num 2) [num (range 100)] (= (% num 2) 1))') == [
         pow(num, 2) for num in range(100) if num % 2 == 1]

tests/native_tests/language.hy

@@ -920,48 +920,48 @@
 
 (defn test-list-comprehensions []
   "NATIVE: test list comprehensions"
-  (assert (= (list-comp (* x 2) (x (range 2))) [0 2]))
+  (assert (= (list-comp (* x 2) [x (range 2)]) [0 2]))
-  (assert (= (list-comp (* x 2) (x (range 4)) (% x 2)) [2 6]))
+  (assert (= (list-comp (* x 2) [x (range 4)] (% x 2)) [2 6]))
-  (assert (= (sorted (list-comp (* y 2) ((, x y) (.items {"1" 1 "2" 2}))))
+  (assert (= (sorted (list-comp (* y 2) [(, x y) (.items {"1" 1 "2" 2})]))
              [2 4]))
-  (assert (= (list-comp (, x y) (x (range 2) y (range 2)))
+  (assert (= (list-comp (, x y) [x (range 2) y (range 2)])
              [(, 0 0) (, 0 1) (, 1 0) (, 1 1)]))
-  (assert (= (list-comp j (j [1 2])) [1 2])))
+  (assert (= (list-comp j [j [1 2]]) [1 2])))
 
 
 (defn test-set-comprehensions []
   "NATIVE: test set comprehensions"
   (assert (instance? set (set-comp x [x (range 2)])))
-  (assert (= (set-comp (* x 2) (x (range 2))) (set [0 2])))
+  (assert (= (set-comp (* x 2) [x (range 2)]) (set [0 2])))
-  (assert (= (set-comp (* x 2) (x (range 4)) (% x 2)) (set [2 6])))
+  (assert (= (set-comp (* x 2) [x (range 4)] (% x 2)) (set [2 6])))
-  (assert (= (set-comp (* y 2) ((, x y) (.items {"1" 1 "2" 2})))
+  (assert (= (set-comp (* y 2) [(, x y) (.items {"1" 1 "2" 2})])
              (set [2 4])))
-  (assert (= (set-comp (, x y) (x (range 2) y (range 2)))
+  (assert (= (set-comp (, x y) [x (range 2) y (range 2)])
              (set [(, 0 0) (, 0 1) (, 1 0) (, 1 1)])))
-  (assert (= (set-comp j (j [1 2])) (set [1 2]))))
+  (assert (= (set-comp j [j [1 2]]) (set [1 2]))))
 
 
 (defn test-dict-comprehensions []
   "NATIVE: test dict comprehensions"
   (assert (instance? dict (dict-comp x x [x (range 2)])))
-  (assert (= (dict-comp x (* x 2) (x (range 2))) {1 2 0 0}))
+  (assert (= (dict-comp x (* x 2) [x (range 2)]) {1 2 0 0}))
-  (assert (= (dict-comp x (* x 2) (x (range 4)) (% x 2)) {3 6 1 2}))
+  (assert (= (dict-comp x (* x 2) [x (range 4)] (% x 2)) {3 6 1 2}))
-  (assert (= (dict-comp x (* y 2) ((, x y) (.items {"1" 1 "2" 2})))
+  (assert (= (dict-comp x (* y 2) [(, x y) (.items {"1" 1 "2" 2})])
              {"2" 4 "1" 2}))
-  (assert (= (dict-comp (, x y) (+ x y) (x (range 2) y (range 2)))
+  (assert (= (dict-comp (, x y) (+ x y) [x (range 2) y (range 2)])
              {(, 0 0) 0 (, 1 0) 1 (, 0 1) 1 (, 1 1) 2})))
 
 
 (defn test-generator-expressions []
   "NATIVE: test generator expressions"
   (assert (not (instance? list (genexpr x [x (range 2)]))))
-  (assert (= (list (genexpr (* x 2) (x (range 2)))) [0 2]))
+  (assert (= (list (genexpr (* x 2) [x (range 2)])) [0 2]))
-  (assert (= (list (genexpr (* x 2) (x (range 4)) (% x 2))) [2 6]))
+  (assert (= (list (genexpr (* x 2) [x (range 4)] (% x 2))) [2 6]))
-  (assert (= (list (sorted (genexpr (* y 2) ((, x y) (.items {"1" 1 "2" 2})))))
+  (assert (= (list (sorted (genexpr (* y 2) [(, x y) (.items {"1" 1 "2" 2})])))
              [2 4]))
-  (assert (= (list (genexpr (, x y) (x (range 2) y (range 2))))
+  (assert (= (list (genexpr (, x y) [x (range 2) y (range 2)]))
              [(, 0 0) (, 0 1) (, 1 0) (, 1 1)]))
-  (assert (= (list (genexpr j (j [1 2]))) [1 2])))
+  (assert (= (list (genexpr j [j [1 2]])) [1 2])))
 
 
 (defn test-defn-order []
@@ -1370,7 +1370,7 @@
 
 (defn test-lambda-keyword-lists []
   "NATIVE: test lambda keyword lists"
-  (defn foo (x &rest xs &kwargs kw) [x xs kw])
+  (defn foo [x &rest xs &kwargs kw] [x xs kw])
   (assert (= (foo 10 20 30) [10 (, 20 30) {}])))
 
 
@@ -1721,7 +1721,7 @@ macros()
 (defmacro identify-keywords [&rest elts]
   `(list
     (map
-     (fn (x) (if (is-keyword x) "keyword" "other"))
+     (fn [x] (if (is-keyword x) "keyword" "other"))
      ~elts)))
 
 (defn test-keywords-and-macros []