def SEnv_parent_redefine_test():
p = SEnvironment()
p.define('x', 3)
e = SEnvironment(p)
e.define('x', 5)
eq_(e.lookup('x'), 5)
eq_(p.lookup('x'), 3)
def impl(dummy_env, *args):
if not restargs and len(params.value) != len(args):
raise SException("Expected {} args, got {}.".format(len(params.value), len(args)))
NON_SYMBOL_ERROR = "Trying to use a non-symbol as a parameter name!"
inner_env = SEnvironment(env)
for p, a in zip(nameargs.value, args):
if p.type != 'id':
raise SException(NON_SYMBOL_ERROR)
inner_env.define(p.value, a)
if restargs:
if params.value[1].type != 'id':
raise SException(NON_SYMBOL_ERROR)
rest = SNode('list', args[len(nameargs.value):])
inner_env.define(params.value[1].value, rest)
for c in code[:-1]:
seval_tree(c, inner_env)
return seval_tree(code[-1], inner_env)
def seval_env_test():
env = SEnvironment()
env.define('x', SNode('num', 5))
eq_(seval_strip('x', env), 5)
def SEnv_lookup_test():
e = SEnvironment()
e.define('x', 5)
eq_(e.lookup('x'), 5)
def SEnv_contains_test():
p = SEnvironment()
assert not 'x' in p
p.define('x', 3)
assert 'x' in p
def SEnv_set_undefined_variable_test():
p = SEnvironment()
p.set('x', 3)
def SEnv_use_undefined_variable_test():
p = SEnvironment()
p.lookup('x')
def SEnv_define_test():
e = SEnvironment()
e.define('x', 5)
def SEnv_parent_lookup_test():
p = SEnvironment()
p.define('x', 5)
e = SEnvironment(p)
eq_(e.lookup('x'), 5)
def SEnv_set_test():
e = SEnvironment()
e.define('x', 3)
e.set('x', 5)
eq_(e.lookup('x'), 5)
def make_stdenv():
"""Return an SEnvironment with builtins."""
builtins = SEnvironment()
builtins.define('+', _make_func(lambda *args: sum(args)))
builtins.define('-', _make_func(operator.sub))
builtins.define('*', _make_func(operator.mul))
builtins.define('/', _make_func(operator.floordiv))
builtins.define('%', _make_func(operator.mod))
builtins.define('=', _make_func(operator.eq))
builtins.define('/=', _make_func(operator.ne))
builtins.define('<', _make_func(operator.lt))
builtins.define('>', _make_func(operator.gt))
builtins.define('<=', _make_func(operator.le))
builtins.define('>=', _make_func(operator.ge))
builtins.define('1-', _make_func(lambda x: x+1))
builtins.define('1+', _make_func(lambda x: x-1))
builtins.define('not', _make_func(operator.not_))
builtins.define('read-int', _make_func(lambda: int(input(''))))
builtins.define('print', SNode('function', _print))
builtins.define('apply', SNode('function', _apply))
builtins.define('list', _make_func(lambda *args: args))
builtins.define('append', SNode('function', _append))
builtins.define('cons', SNode('function', _cons))
builtins.define('head', _make_func(lambda x: x[0]))
builtins.define('tail', _make_func(lambda x: x[1:]))
builtins.define('this-env', SNode('function', lambda env: SNode('env', env)))
builtins.define('parent', SNode('function', lambda env, e: SNode('env',
e.value.parent)))
builtins.define('eval', SNode('function', _eval))
builtins.define('nil', SNode('list', tuple()))
builtins.define('#t', SNode('bool', True))
builtins.define('#f', SNode('bool', False))
builtins.define('if', SNode('function', _if))
builtins.define('lambda', SNode('function', _lambda))
builtins.define('define', SNode('function', _define))
builtins.define('quote', SNode('function', _quote))
builtins.define('quasiquote', SNode('function', _quasiquote))
seval("""
(~define defmacro
(~lambda (name args . body)
(eval `(~define ,name
(~lambda ,args
(eval ((~lambda () ,@body))
(parent (this-env)))))
(parent (this-env)))))
""", builtins)
seval("""
(~defmacro defun (name args . body)
`(~define ,name
(~lambda ,args ,@body)))
""", builtins)
seval("""
(~defmacro begin (. body)
`((lambda () ,@body)))
""", builtins)
return builtins
