def test_cons(self):
program = "(cons 1 (quote (2 3)))"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(2),
Integer(3)]))
program = "(cons 1 2)"
self.assertEvaluatesTo(program, Cons(Integer(1), Integer(2)))
def test_variadic_function_definition(self):
# test that we can put nothing in the impure list parameter
program = "(define (foo . args) 1) (foo)"
self.assertEvaluatesTo(program, Integer(1))
# test that we can put multiple things in the impure list parameter
program = "(define (f . everything) everything) (f 1 2 3)"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(2),
Integer(3)]))
# test that the improper list parameter is evaluated
program = "(define (g . everything) everything) (g (+ 2 3))"
self.assertEvaluatesTo(program, Cons(Integer(5)))
def test_cdr(self):
program = "(cdr (quote (1 2 3)))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(2), Integer(3)]))
program = "(cdr (quote (1 2 3)) 1)"
with self.assertRaises(SchemeArityError):
self.evaluate(program)
def test_list(self):
program = "(list)"
self.assertEvaluatesTo(program, Nil())
program = "(list 1 (+ 2 3))"
self.assertEvaluatesTo(program,
Cons.from_list([Integer(1),
Integer(5)]))
def test_quasiquote_sugar(self):
program = "`,1"
self.assertEvaluatesTo(program, Integer(1))
program = "`(1 ,@'(2 2))"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(2),
Integer(2)]))
def test_cdr(self):
program = "(cdr (quote (1 2 3)))"
self.assertEvaluatesTo(program,
Cons.from_list([Integer(2),
Integer(3)]))
program = "(cdr (quote (1 2 3)) 1)"
with self.assertRaises(SchemeArityError):
self.evaluate(program)
def test_quote(self):
program = "(quote (1 2 3))"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(2),
Integer(3)]))
program = "(quote ())"
self.assertEvaluatesTo(program, Nil())
def test_variadic_function_definition(self):
# test that we can put nothing in the impure list parameter
program = "(define (foo . args) 1) (foo)"
self.assertEvaluatesTo(program, Integer(1))
# test that we can put multiple things in the impure list parameter
program = "(define (f . everything) everything) (f 1 2 3)"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2), Integer(3)]))
# test that the improper list parameter is evaluated
program = "(define (g . everything) everything) (g (+ 2 3))"
self.assertEvaluatesTo(program, Cons(Integer(5)))
def test_car_cdr_compositions(self):
program = "(caar '((1 3) 2))"
self.assertEvaluatesTo(program, Integer(1))
program = "(cadr '((1 3) 2))"
self.assertEvaluatesTo(program, Integer(2))
program = "(cdar '((1 3) 2))"
self.assertEvaluatesTo(program, Cons(Integer(3)))
program = "(cddr '((1 3) 2))"
self.assertEvaluatesTo(program, Nil())
def test_quasiquote(self):
program = "(quasiquote (1 1))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(1)]))
program = "(quasiquote (unquote 1))"
self.assertEvaluatesTo(program, Integer(1))
program = "(quasiquote (1 (unquote (+ 2 2))))"
self.assertEvaluatesTo(program, Cons(Integer(1), Cons(Integer(4))))
program = "(quasiquote (1 (unquote-splicing '(2 2))))"
self.assertEvaluatesTo(program, Cons(Integer(1), Cons(Integer(2), Cons(Integer(2)))))
def recursive_eval_unquote(s_expression, _environment):
"""Return a copy of s_expression, with all occurrences of
unquoted s-expressions replaced by their evaluated values.
Note that we can only have unquote-splicing in a sublist,
since we can only return one value, e.g `,@(1 2 3).
"""
if isinstance(s_expression, Atom):
return (s_expression, _environment)
elif isinstance(s_expression, Nil):
return (s_expression, _environment)
elif s_expression[0] == Symbol("unquote"):
check_argument_number('unquote', arguments, 1, 1)
return eval_s_expression(s_expression[1], _environment)
else:
# return a list of s_expressions that have been
# recursively checked for unquote
list_elements = []
for element in s_expression:
if isinstance(element, Cons) and \
element[0] == Symbol('unquote-splicing'):
check_argument_number('unquote-splicing', element.tail, 1,
1)
(result,
_environment) = eval_s_expression(element[1],
_environment)
if not isinstance(result, Cons) and not isinstance(
result, Nil):
raise SchemeArityError(
"unquote-splicing requires a list.")
for item in result:
list_elements.append(item)
else:
(result, _environment) = recursive_eval_unquote(
element, _environment)
list_elements.append(result)
return (Cons.from_list(list_elements), _environment)
def test_quasiquote(self):
program = "(quasiquote (1 1))"
self.assertEvaluatesTo(program,
Cons.from_list([Integer(1),
Integer(1)]))
program = "(quasiquote (unquote 1))"
self.assertEvaluatesTo(program, Integer(1))
program = "(quasiquote (1 (unquote (+ 2 2))))"
self.assertEvaluatesTo(program, Cons(Integer(1), Cons(Integer(4))))
program = "(quasiquote (1 (unquote-splicing '(2 2))))"
self.assertEvaluatesTo(
program, Cons(Integer(1), Cons(Integer(2), Cons(Integer(2)))))
def expand_then_eval(arguments, _environment):
"""Expand this macro once, then continue evaluation."""
if is_variadic:
if len(arguments) < len(macro_arguments):
raise SchemeArityError(
"Macro %s takes at least %d arguments, but got %d." %
(macro_name, len(macro_arguments), len(arguments)))
else:
if len(arguments) != len(macro_arguments):
raise SchemeArityError(
"Macro %s takes %d arguments, but got %d." %
(macro_name, len(macro_arguments), len(arguments)))
new_environment = dict(_environment)
for (variable_name, variable_value) in zip(macro_arguments, arguments):
new_environment[variable_name] = variable_value
if is_variadic:
remaining_arguments = []
for index, arg in enumerate(arguments):
if index >= len(macro_arguments):
remaining_arguments.append(arg)
new_environment[variadic_argument_name] = Cons.from_list(
remaining_arguments)
(s_expression_after_expansion,
new_environment) = eval_s_expression(replacement_body,
new_environment)
# restore old environment, ignoring variables hidden by scope
for variable_name in _environment:
if variable_name not in macro_arguments:
_environment[variable_name] = new_environment[variable_name]
# continue evaluation where we left off
return eval_s_expression(s_expression_after_expansion, _environment)
def test_vector_to_list(self):
program = "(vector->list (vector 1 2))"
self.assertEvaluatesTo(program,
Cons.from_list([Integer(1),
Integer(2)]))
def p_list_unquotesplicingsugar(p):
"list : UNQUOTESPLICINGSUGAR sexpression"
# convert ,foo to (unquote foo)
p[0] = Cons(Symbol("unquote-splicing"), Cons(p[2]))
def test_set_car(self):
program = "(define x (list 4 5 6)) (set-car! x 1) x"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(5), Integer(6)]))
def test_quasiquote_sugar(self):
program = "`,1"
self.assertEvaluatesTo(program, Integer(1))
program = "`(1 ,@'(2 2))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2), Integer(2)]))
def test_quote_sugar(self):
program = "'(1 2 3)"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2), Integer(3)]))
def test_quote_sugar(self):
program = "'(1 2 3)"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(2),
Integer(3)]))
def cons(arguments):
# TODO: check type as well as arity
check_argument_number('cons', arguments, 2, 2)
return Cons(arguments[0], arguments[1])
def test_set_car(self):
program = "(define x (list 4 5 6)) (set-car! x 1) x"
self.assertEvaluatesTo(
program, Cons.from_list([Integer(1),
Integer(5),
Integer(6)]))
def test_quote(self):
program = "(quote (1 2 3))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2), Integer(3)]))
program = "(quote ())"
self.assertEvaluatesTo(program, Nil())
def test_set_cdr(self):
program = "(define x (list 4 5 6)) (set-cdr! x 1) x"
result = self.evaluate(program)
self.assertEqual(result, Cons(Integer(4), Integer(1)))
def test_list(self):
program = "(list)"
self.assertEvaluatesTo(program, Nil())
program = "(list 1 (+ 2 3))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(5)]))
def p_list_quasiquotesugar(p):
"list : QUASIQUOTESUGAR sexpression"
# convert `foo to (quasiquote foo)
p[0] = Cons(Symbol("quasiquote"), Cons(p[2]))
def p_list_unquotesugar(p):
"list : UNQUOTESUGAR sexpression"
# convert ,foo to (unquote foo)
p[0] = Cons(Symbol("unquote"), Cons(p[2]))
def test_map(self):
program = "(map (lambda (x) (+ x 1)) '(2 3))"
self.assertEvaluatesTo(program, Cons(Integer(3), Cons(Integer(4))))
def test_cons(self):
program = "(cons 1 (quote (2 3)))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2), Integer(3)]))
program = "(cons 1 2)"
self.assertEvaluatesTo(program, Cons(Integer(1), Integer(2)))
def p_listarguments_one(p):
"listarguments : sexpression listarguments"
# a list is therefore a nested tuple:
p[0] = Cons(p[1], p[2])
def test_vector_to_list(self):
program = "(vector->list (vector 1 2))"
self.assertEvaluatesTo(program, Cons.from_list([Integer(1), Integer(2)]))
def p_program(p):
"program : sexpression program"
p[0] = Cons(p[1], p[2])
