Merge pull request #781 from zackmdavis/kwonly_connect
keyword-only arguments
This commit is contained in:
Morten Linderud
commit
73a29fd377
@ -441,6 +441,41 @@ Parameters may have the following keywords in front of them:
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=> (zig-zag-sum 1 2 3 4 5 6)
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-3
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&kwonly
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.. versionadded:: 0.12.0
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Parameters that can only be called as keywords. Mandatory
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keyword-only arguments are declared with the argument's name;
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optional keyword-only arguments are declared as a two-element list
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containing the argument name followed by the default value (as
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with `&optional` above).
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.. code-block:: clj
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=> (defn compare [a b &kwonly keyfn [reverse false]]
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... (let [[result (keyfn a b)]]
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... (if (not reverse)
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... result
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... (- result))))
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=> (apply compare ["lisp" "python"]
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... {"keyfn" (fn [x y]
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... (reduce - (map (fn [s] (ord (first s))) [x y])))})
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-4
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=> (apply compare ["lisp" "python"]
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... {"keyfn" (fn [x y]
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... (reduce - (map (fn [s] (ord (first s))) [x y])))
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... "reverse" true})
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4
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.. code-block:: python
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=> (compare "lisp" "python")
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Traceback (most recent call last):
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File "<input>", line 1, in <module>
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TypeError: compare() missing 1 required keyword-only argument: 'keyfn'
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Availability: Python 3.
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.. _defn-alias / defun-alias:
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defn-alias / defun-alias
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@ -485,11 +485,13 @@ class HyASTCompiler(object):
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def _parse_lambda_list(self, exprs):
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""" Return FunctionDef parameter values from lambda list."""
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ll_keywords = ("&rest", "&optional", "&key", "&kwargs")
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ll_keywords = ("&rest", "&optional", "&key", "&kwonly", "&kwargs")
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ret = Result()
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args = []
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defaults = []
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varargs = None
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kwonlyargs = []
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kwonlydefaults = []
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kwargs = None
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lambda_keyword = None
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@ -506,6 +508,8 @@ class HyASTCompiler(object):
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lambda_keyword = expr
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elif expr == "&key":
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lambda_keyword = expr
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elif expr == "&kwonly":
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lambda_keyword = expr
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elif expr == "&kwargs":
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lambda_keyword = expr
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else:
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@ -554,6 +558,24 @@ class HyASTCompiler(object):
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args.append(k)
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ret += self.compile(v)
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defaults.append(ret.force_expr)
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elif lambda_keyword == "&kwonly":
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if not PY3:
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raise HyTypeError(expr,
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"keyword-only arguments are only "
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"available under Python 3")
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if isinstance(expr, HyList):
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if len(expr) != 2:
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raise HyTypeError(expr,
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"keyword-only args should be bare "
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"names or 2-item lists")
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k, v = expr
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kwonlyargs.append(k)
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ret += self.compile(v)
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kwonlydefaults.append(ret.force_expr)
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else:
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k = expr
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kwonlyargs.append(k)
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kwonlydefaults.append(None)
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elif lambda_keyword == "&kwargs":
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if kwargs:
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raise HyTypeError(expr,
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@ -561,7 +583,7 @@ class HyASTCompiler(object):
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"&kwargs argument")
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kwargs = str(expr)
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return ret, args, defaults, varargs, kwargs
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return ret, args, defaults, varargs, kwonlyargs, kwonlydefaults, kwargs
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def _storeize(self, name, func=None):
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"""Return a new `name` object with an ast.Store() context"""
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@ -2026,7 +2048,9 @@ class HyASTCompiler(object):
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if not isinstance(arglist, HyList):
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raise HyTypeError(expression,
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"First argument to (fn) must be a list")
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ret, args, defaults, stararg, kwargs = self._parse_lambda_list(arglist)
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(ret, args, defaults, stararg,
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kwonlyargs, kwonlydefaults, kwargs) = self._parse_lambda_list(arglist)
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for i, arg in enumerate(args):
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if isinstance(arg, HyList):
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# Destructuring argument
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@ -2049,6 +2073,11 @@ class HyASTCompiler(object):
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lineno=x.start_line,
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col_offset=x.start_column) for x in args]
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kwonlyargs = [ast.arg(arg=ast_str(x), annotation=None,
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lineno=x.start_line,
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col_offset=x.start_column)
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for x in kwonlyargs]
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# XXX: Beware. Beware. This wasn't put into the parse lambda
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# list because it's really just an internal parsing thing.
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@ -2065,12 +2094,18 @@ class HyASTCompiler(object):
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lineno=x.start_line,
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col_offset=x.start_column) for x in args]
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if PY3:
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kwonlyargs = [ast.Name(arg=ast_str(x), id=ast_str(x),
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ctx=ast.Param(), lineno=x.start_line,
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col_offset=x.start_column)
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for x in kwonlyargs]
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args = ast.arguments(
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args=args,
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vararg=stararg,
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kwarg=kwargs,
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kwonlyargs=[],
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kw_defaults=[],
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kwonlyargs=kwonlyargs,
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kw_defaults=kwonlydefaults,
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defaults=defaults)
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body = self._compile_branch(expression)
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@ -54,11 +54,13 @@ def cant_compile(expr):
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# error, otherwise it's a compiler bug.
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assert isinstance(e.expression, HyObject)
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assert e.message
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return e
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except HyCompileError as e:
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# Anything that can't be compiled should raise a user friendly
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# error, otherwise it's a compiler bug.
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assert isinstance(e.exception, HyTypeError)
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assert e.traceback
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return e
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def test_ast_bad_type():
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@ -441,10 +443,31 @@ def test_lambda_list_keywords_kwargs():
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cant_compile("(fn (x &kwargs xs &kwargs ys) (list x xs ys))")
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def test_lambda_list_keywords_kwonly():
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"""Ensure we can compile functions with &kwonly if we're on Python
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3, or fail with an informative message on Python 2."""
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kwonly_demo = "(fn [&kwonly a [b 2]] (print a b))"
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if PY3:
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code = can_compile(kwonly_demo)
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for i, kwonlyarg_name in enumerate(('a', 'b')):
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assert kwonlyarg_name == code.body[0].args.kwonlyargs[i].arg
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assert code.body[0].args.kw_defaults[0] is None
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assert code.body[0].args.kw_defaults[1].n == 2
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else:
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exception = cant_compile(kwonly_demo)
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assert isinstance(exception, HyTypeError)
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message, = exception.args
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assert message == ("keyword-only arguments are only "
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"available under Python 3")
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def test_lambda_list_keywords_mixed():
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""" Ensure we can mix them up."""
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can_compile("(fn (x &rest xs &kwargs kw) (list x xs kw))")
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cant_compile("(fn (x &rest xs &fasfkey {bar \"baz\"}))")
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if PY3:
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can_compile("(fn [x &rest xs &kwargs kwxs &kwonly kwoxs]"
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" (list x xs kwxs kwoxs))")
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def test_ast_unicode_strings():
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@ -10,3 +10,29 @@
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(try (raise ValueError :from NameError)
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(except [e [ValueError]]
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(assert (= (type (. e __cause__)) NameError)))))
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(defn test-kwonly []
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"NATIVE: test keyword-only arguments"
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;; keyword-only with default works
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(let [[kwonly-foo-default-false (fn [&kwonly [foo false]] foo)]]
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(assert (= (apply kwonly-foo-default-false) false))
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(assert (= (apply kwonly-foo-default-false [] {"foo" true}) true)))
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;; keyword-only without default ...
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(let [[kwonly-foo-no-default (fn [&kwonly foo] foo)]
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[attempt-to-omit-default (try
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(kwonly-foo-no-default)
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(catch [e [Exception]] e))]]
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;; works
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(assert (= (apply kwonly-foo-no-default [] {"foo" "quux"}) "quux"))
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;; raises TypeError with appropriate message if not supplied
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(assert (isinstance attempt-to-omit-default TypeError))
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(assert (in "missing 1 required keyword-only argument: 'foo'"
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(. attempt-to-omit-default args [0]))))
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;; keyword-only with other arg types works
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(let [[function-of-various-args
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(fn [a b &rest args &kwonly foo &kwargs kwargs]
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(, a b args foo kwargs))]]
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(assert (= (apply function-of-various-args
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[1 2 3 4] {"foo" 5 "bar" 6 "quux" 7})
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(, 1 2 (, 3 4) 5 {"bar" 6 "quux" 7})))))
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