def test_set():
"""Ensure set mutates bindings."""
env = prelude.env()
# ensure we can't set non-existent bindings
bad_call = wtypes.List(
[wtypes.Integer(1),
wtypes.Symbol('x'),
wtypes.Symbol('set!')])
with pytest.raises(exceptions.WispException):
assert bad_call.eval(env)
# ensure we can set previously-existent bindings
define_call = wtypes.List(
[wtypes.Integer(1),
wtypes.Symbol('x'),
wtypes.Symbol('define')])
define_call.eval(env)
assert wtypes.Symbol('x').eval(env) == wtypes.Integer(1)
set_call = wtypes.List(
[wtypes.Integer(2),
wtypes.Symbol('x'),
wtypes.Symbol('set!')])
set_call.eval(env)
assert wtypes.Symbol('x').eval(env) == wtypes.Integer(2)
def test_begin():
"""Ensure begin return the last expression."""
env = prelude.env()
call = wtypes.List([
wtypes.List([
wtypes.Integer(1),
wtypes.Integer(2),
wtypes.Symbol('+'),
]),
wtypes.List([
wtypes.Integer(1),
wtypes.Integer(1),
wtypes.Symbol('+'),
]),
wtypes.Symbol('begin')
])
assert call.eval(env) == wtypes.Integer(3)
def cons(args: typing.List[wtypes.Expression],
env: wisp.env.Environment) -> wtypes.List:
"""Attach the first argument to the head of the list in the second."""
head, rest = args
if isinstance(rest, wtypes.List):
return wtypes.List([head] + rest.items)
else:
raise exceptions.type_error(wtypes.List, rest)
def test_cond():
"""Ensure we evaluate cond properly."""
env = prelude.env()
call = wtypes.List([
wtypes.List([
wtypes.String('two'),
wtypes.List(
[wtypes.Integer(2),
wtypes.Integer(2),
wtypes.Symbol('eq?')])
]),
wtypes.List([
wtypes.String('one'),
wtypes.List(
[wtypes.Integer(1),
wtypes.Integer(1),
wtypes.Symbol('eq?')])
]),
wtypes.List([
wtypes.String('not-one'),
wtypes.List(
[wtypes.Integer(2),
wtypes.Integer(1),
wtypes.Symbol('eq?')])
]),
wtypes.Symbol('cond')
])
result = call.eval(env)
assert result == wtypes.String('one')
def test_eval_list():
"""Ensure lists are evaluated as post-fix function calls."""
env = wisp.env.Environment({'+': wtypes.Function(
lambda xs, _: wtypes.Integer(xs[0].val + xs[1].val)
)})
res = wtypes.List([
wtypes.Integer(1), wtypes.Integer(2), wtypes.Symbol('+')
]).eval(env)
assert res == wtypes.Integer(3)
def test_cdr():
"""Ensure cdr takes the rest."""
env = prelude.env()
res = env[wtypes.Symbol('cdr')].call([
quoted_list([wtypes.Integer(1),
wtypes.Integer(2),
wtypes.Integer(3)])
], env)
assert res == wtypes.List([wtypes.Integer(2), wtypes.Integer(3)])
def test_bad_lambda():
"""Ensure we handle lambdas which raise exceptions."""
env = prelude.env()
# define a lambda calling a non-existent symbol
bad_lambda = env[wtypes.Symbol('lambda')].call([
wtypes.List([wtypes.Symbol('x')]),
wtypes.List([wtypes.Symbol('snakes')])
], env)
# raise an exception when we call it
call = wtypes.List([wtypes.Integer(2), bad_lambda])
with pytest.raises(exceptions.WispException):
call.eval(env)
# ensure we didn't pollute even though the call raised an exception
with pytest.raises(exceptions.WispException):
env[wtypes.Symbol('x')]
def test_define():
"""Ensure define binds values to symbols."""
env = prelude.env()
res = env[wtypes.Symbol('define')].call(
[wtypes.Symbol('a'),
quoted_list([wtypes.String('apple')])], env)
assert res == wtypes.Symbol('a')
assert env[wtypes.Symbol('a')] == wtypes.List([wtypes.String('apple')])
def test_parse_list():
"""Ensure we can parse lists."""
assert parser.parse_expr.parse('(1 abc "abc" #t #f +)') == wtypes.List([
wtypes.Integer(1),
wtypes.Symbol('abc'),
wtypes.String('abc'),
wtypes.Bool(True),
wtypes.Bool(False),
wtypes.Symbol('+'),
])
def test_cons():
"""Ensure cons sticks things together."""
env = prelude.env()
res = env[wtypes.Symbol('cons')].call([
wtypes.Integer(1),
quoted_list([wtypes.Integer(2), wtypes.Integer(3)])
], env)
assert res == wtypes.List(
[wtypes.Integer(1),
wtypes.Integer(2),
wtypes.Integer(3)])
def test_lambda():
"""Ensure lambdas can be defined and called."""
env = prelude.env()
# define a lambda performing x - y
sub_lambda = env[wtypes.Symbol('lambda')].call([
wtypes.List([wtypes.Symbol('x'),
wtypes.Symbol('y')]),
wtypes.List(
[wtypes.Symbol('y'),
wtypes.Symbol('x'),
wtypes.Symbol('-')]),
], env)
# ensure we can call the above lambda
call = wtypes.List([wtypes.Integer(1), wtypes.Integer(3), sub_lambda])
res = call.eval(env)
assert res == wtypes.Integer(2)
# ensure we didn't pollute the environment with bindings from the call.
with pytest.raises(exceptions.WispException):
env[wtypes.Symbol('x')]
def test_cond_with_else():
"""Ensure we handle else expressions."""
env = prelude.env()
call = wtypes.List([
wtypes.List([wtypes.String('else-case'),
wtypes.Symbol('else')]),
wtypes.List([
wtypes.String('not-two'),
wtypes.List(
[wtypes.Integer(3),
wtypes.Integer(2),
wtypes.Symbol('eq?')])
]),
wtypes.List([
wtypes.String('not-one'),
wtypes.List(
[wtypes.Integer(2),
wtypes.Integer(1),
wtypes.Symbol('eq?')])
]),
wtypes.Symbol('cond')
])
result = call.eval(env)
assert result == wtypes.String('else-case')
def quoted_list(elems):
"""Build a quoted list consisting of the given elements, safe from eval."""
return wtypes.List([wtypes.List(elems), wtypes.Symbol('quote')])
def test_closures():
"""Ensure we handle closures properly."""
env = prelude.env()
counter_def = wtypes.List([
wtypes.List([
wtypes.List([
wtypes.List([
wtypes.Symbol('x'),
wtypes.List([
wtypes.List([
wtypes.Integer(1),
wtypes.Symbol('x'),
wtypes.Symbol('+')
]),
wtypes.Symbol('x'),
wtypes.Symbol('set!')
]),
wtypes.Symbol('begin')
]),
wtypes.List([]),
wtypes.Symbol('lambda')
]),
wtypes.List([wtypes.Symbol('x')]),
wtypes.Symbol('lambda')
]),
wtypes.Symbol('make-counter'),
wtypes.Symbol('define'),
])
counter_def.eval(env)
counter = wtypes.List([
wtypes.List([wtypes.Integer(0),
wtypes.Symbol('make-counter')]),
wtypes.Symbol('c'),
wtypes.Symbol('define'),
])
counter.eval(env)
call = wtypes.List([wtypes.Symbol('c')])
assert call.eval(env) == wtypes.Integer(1)
assert call.eval(env) == wtypes.Integer(2)
assert call.eval(env) == wtypes.Integer(3)
# ensure 'x' from the closure hasn't leaked into the global scope.
with pytest.raises(exceptions.WispException):
env[wtypes.Symbol('x')]
def test_recursion():
"""Ensure we can handle simple recursion."""
env = prelude.env()
fib_def = wtypes.List([
wtypes.List([
wtypes.List([
wtypes.List([
wtypes.List([
wtypes.List([
wtypes.List([
wtypes.Integer(2),
wtypes.Symbol('n'),
wtypes.Symbol('-')
]),
wtypes.Symbol('fib')
]),
wtypes.List([
wtypes.List([
wtypes.Integer(1),
wtypes.Symbol('n'),
wtypes.Symbol('-')
]),
wtypes.Symbol('fib')
]),
wtypes.Symbol('+')
]),
wtypes.Symbol('else')
]),
wtypes.List([
wtypes.Integer(1),
wtypes.List([
wtypes.Integer(1),
wtypes.Symbol('n'),
wtypes.Symbol('eq?')
])
]),
wtypes.List([
wtypes.Integer(0),
wtypes.List([
wtypes.Integer(0),
wtypes.Symbol('n'),
wtypes.Symbol('eq?')
])
]),
wtypes.Symbol('cond')
]),
wtypes.List([wtypes.Symbol('n')]),
wtypes.Symbol('lambda')
]),
wtypes.Symbol('fib'),
wtypes.Symbol('define'),
])
fib_def.eval(env)
call = wtypes.List([wtypes.Integer(0), wtypes.Symbol('fib')])
assert call.eval(env) == wtypes.Integer(0)
call = wtypes.List([wtypes.Integer(1), wtypes.Symbol('fib')])
assert call.eval(env) == wtypes.Integer(1)
call = wtypes.List([wtypes.Integer(5), wtypes.Symbol('fib')])
assert call.eval(env) == wtypes.Integer(5)
call = wtypes.List([wtypes.Integer(6), wtypes.Symbol('fib')])
assert call.eval(env) == wtypes.Integer(8)
call = wtypes.List([wtypes.Integer(7), wtypes.Symbol('fib')])
assert call.eval(env) == wtypes.Integer(13)
def test_eval_empty_list():
"""Ensure empty lists are evaluated to empty lists."""
assert wtypes.List([]).eval({}) == wtypes.List([])
def cdr(args: typing.List[wtypes.Expression],
env: wisp.env.Environment) -> wtypes.List:
"""Return all but the first element of the given list."""
return __list_op(lambda wlst: wtypes.List(wlst.items[1:]), args)
def test_eval_list_without_a_func():
"""Ensure an error is raised when applying non-functions."""
with pytest.raises(exceptions.WispException):
wtypes.List([wtypes.Integer(1)]).eval({})
def parse_list():
"""Parse a list as a ()-enclosed sequence of expressions."""
yield parsec.string('(')
vals = yield parsec.sepBy(parse_expr, parsec.many1(parsec.space()))
yield parsec.string(')')
return wtypes.List(vals)