def test_lambda_arguments_are_lists():
"""The parameters of a `lambda` should be a list."""
closure = evaluate(parse("(lambda (x y) (+ x y))"), Environment())
assert_true(is_list(closure.params))
with assert_raises(LispError):
evaluate(parse("(lambda not-a-list (body of fn))"), Environment())
def unparse(ast):
"""Turns an AST back into lisp program source"""
if is_boolean(ast):
return "#t" if ast else "#f"
elif is_list(ast):
if len(ast) > 0 and ast[0] == "quote":
return "'%s" % unparse(ast[1])
else:
return "(%s)" % " ".join([unparse(x) for x in ast])
else:
# integers or symbols (or lambdas)
return str(ast)
def unparse(ast):
"""Turns an AST back into lisp program source"""
if is_boolean(ast):
return "#t" if ast else "#f"
elif is_list(ast):
if len(ast) > 0 and ast[0] == "quote":
return "'%s" % unparse(ast[1])
else:
return "(%s)" % " ".join([unparse(x) for x in ast])
else:
# integers or symbols (or lambdas)
return str(ast)