def A_native_function_can_edit_the_environment():
def mx3(env):
env.set("x", ("number", 3))
env = Env()
env.set("make_x_three", ("native", mx3))
assert_that(evald("x=1;make_x_three();x;", env), equals(("number", 3)))
def A_closure_holds_updateable_values():
def dumb_set(env, sym, val):
env.parent.parent.parent.set(sym[1], val)
def dumb_if_equal(env, val1, val2, then_fn, else_fn):
if val1 == val2:
ret = then_fn
else:
ret = else_fn
return eval_expr(("call", ret, []), env)
env = Env()
env.set("dumb_set", ("native", dumb_set))
env.set("dumb_if_equal", ("native", dumb_if_equal))
assert_that(
evald(
"""
counter = {
x = 0;
{:(meth)
dumb_if_equal(meth, "get",
{x;},
{dumb_set("x", x + 1);}
);
}
}();
counter("inc");
counter("inc");
counter("get");
""", env), equals(("number", 2)))
def Native_function_gets_called():
def native_fn(env, x, y):
return ("number", x[1] + y[1])
env = Env()
env.set("native_fn", ("native", native_fn))
assert_that(evald("native_fn( 2, 8 );", env), equals(("number", 10)))
def A_closure_holds_updateable_values():
def dumb_set(env, sym, val):
env.parent.parent.parent.set(sym[1], val)
def dumb_if_equal(env, val1, val2, then_fn, else_fn):
if val1 == val2:
ret = then_fn
else:
ret = else_fn
return eval_expr(("call", ret, []), env)
env = Env()
env.set("dumb_set", ("native", dumb_set))
env.set("dumb_if_equal", ("native", dumb_if_equal))
assert_that(
evald(
"""
counter = {
x = 0;
{:(meth)
dumb_if_equal(meth, "get",
{x;},
{dumb_set("x", x + 1);}
);
}
}();
counter("inc");
counter("inc");
counter("get");
""",
env
),
equals(("number", 2))
)
def A_native_function_can_edit_the_environment():
def mx3(env):
env.set("x", ("number", 3))
env = Env()
env.set("make_x_three", ("native", mx3))
assert_that(
evald("x=1;make_x_three();x;", env),
equals(("number", 3))
)
def Wrong_number_of_arguments_to_a_native_function_is_an_error():
def native_fn0(env):
return ("number", 12)
def native_fn3(env, x, y, z):
return ("number", 12)
env = Env()
env.set("native_fn0", ("native", native_fn0))
env.set("native_fn3", ("native", native_fn3))
assert_prog_fails(
"native_fn0(3);",
"1 arguments passed to function ('symbol', 'native_fn0'), but it requires 0 arguments.",
env)
assert_prog_fails(
"native_fn3(3, 2);",
"2 arguments passed to function ('symbol', 'native_fn3'), but it requires 3 arguments.",
env)
def Wrong_number_of_arguments_to_a_native_function_is_an_error():
def native_fn0(env):
return ("number", 12)
def native_fn3(env, x, y, z):
return ("number", 12)
env = Env()
env.set("native_fn0", ("native", native_fn0))
env.set("native_fn3", ("native", native_fn3))
assert_prog_fails(
"native_fn0(3);",
"1 arguments passed to function ('symbol', 'native_fn0'), but it requires 0 arguments.",
env
)
assert_prog_fails(
"native_fn3(3, 2);",
"2 arguments passed to function ('symbol', 'native_fn3'), but it requires 3 arguments.",
env
)
def _function_call(expr, env):
fn = eval_expr(expr[1], env)
args = list((eval_expr(a, env) for a in expr[2]))
if fn[0] == "function":
params = fn[1]
fail_if_wrong_number_of_args(expr[1], params, args)
body = fn[2]
fn_env = fn[3]
new_env = Env(fn_env)
for p, a in zip(params, args):
new_env.set(p[1], a)
return eval_list(body, new_env)
elif fn[0] == "native":
py_fn = fn[1]
params = inspect.getargspec(py_fn).args
fail_if_wrong_number_of_args(expr[1], params[1:], args)
return fn[1](env, *args)
else:
raise Exception(
"Attempted to call something that is not a function: %s" % str(fn))
def _function_call(expr, env):
fn = eval_expr(expr[1], env)
args = list((eval_expr(a, env) for a in expr[2]))
if fn[0] == "function":
params = fn[1]
fail_if_wrong_number_of_args(expr[1], params, args)
body = fn[2]
fn_env = fn[3]
new_env = Env(fn_env)
for p, a in zip(params, args):
new_env.set(p[1], a)
return eval_list(body, new_env)
elif fn[0] == "native":
py_fn = fn[1]
params = inspect.getargspec(py_fn).args
fail_if_wrong_number_of_args(expr[1], params[1:], args)
return fn[1](env, *args)
else:
raise Exception(
"Attempted to call something that is not a function: %s" %
str(fn)
)
def Native_function_gets_called():
def native_fn(env, x, y):
return ("number", x[1] + y[1])
env = Env()
env.set("native_fn", ("native", native_fn))
assert_that(evald("native_fn( 2, 8 );", env), equals(("number", 10)))