def test_expand_simple_macro_once(self):
"""expand-1 should expand macro call expression once"""
env = default_env()
interpret("""(define swp
(macro (foo bar)
(list bar foo)))""", env)
assert_equals("(42 #t)", interpret("(expand-1 '(swp #t 42))", env))
def test_if_with_variable_lookup(self):
"""Test evaluation of expressions (variable lookup) within if form"""
env = default_env()
interpret("(define pred #f)", env)
interpret("(define else 42)", env)
assert_equals("42", interpret("(if pred then else)", env))
def test_factorial(self):
"""Simple factorial"""
env = default_env()
interpret("""
(define fact
(lambda (n)
(if (<= n 1)
1
(* n (fact (- n 1))))))
""", env)
assert_equals("120", interpret("(fact 5)", env))
def IGNORED_test_check_nil_test_fn(self):
"""Test the `nil?` function
`nil?` returns #t on empty lists, and #f otherwise"""
env = default_env()
assert_equals("#t", interpret("(nil? (list))"))
assert_equals("#t", interpret("(nil? 'nil)"))
assert_equals("#t", interpret("(nil? (cdr (list 1)))"))
assert_equals("#f", interpret("(nil? 'foo)"))
assert_equals("#f", interpret("(nil? (list 'foo 'bar))"))
def test_gcd(self):
"""Greates common dividor"""
env = default_env()
interpret("""
(define gcd
(lambda (a b)
(if (= 0 b)
a
(gcd b (mod a b)))))
""", env)
assert_equals("6", interpret("(gcd 108 30)", env))
assert_equals("1", interpret("(gcd 17 5)", env))
