Interpreter Tests

scheme.py

assert seval(23, {}) == 23
assert seval("x", {"x": 23}) == 23
assert seval(("+", 1, 2), env) == 3
assert seval(("+", 1, ("*", 2, 3)), env) == 7

seval(("define", "x", 13), env) == 7
assert seval(("x"), env) == 13

assert seval(("if", ("<", 2, 3), 4, 5), env) == 4
assert seval(("if", (">", 2, 3), 4, 5), env) == 5

assert substitute(('*', ('+', 'x', 'y'), ('x',)), 'x', 2) == ('*', ('+', 2, 'y'), (2,))

factorial = ('define', 'factorial',
        ('lambda', ('n',), ('if', ('=', 'n', 1), 1, ('*', 'n', ('factorial', ('-', 'n', 1))))))

seval(factorial, env)
seval(('define', 'n', 5), env)
result = seval(('fact', 'n'), env)
assert result == 120