Impl. of (scheme base) in Python.

scheme_base.py

"""
scheme_base.py -- by andydude

This is an implementation of (scheme base) in Python.
"""

class char_t(str):
    def __init__(self, o):
        if isinstance(o, int):
            self.__init__(chr(o))
        elif isinstance(o, str):
            self.__init__(o)
        else:
            raise TypeError

class bytevector_t(bytearray):
    def __init__(self, o):
        if isinstance(o, bytes):
            self.__init__(o)
        elif isinstance(o, bytearray):
            self.__init__(o)
        else:
            raise TypeError

class symbol_t(str):
    def __init__(self, o):
        if isinstance(o, str):
            self.__init__(o)
        else:
            raise TypeError

def append(*lists):
    return sum(lists, [])

def begin(*args):
    return args[-1]

def null_q(o):
    return isinstance(o, list) and len(o) == 0

def pair_q(o):
    return isinstance(o, list) and len(o) > 0

def cons(a, b):
    assert isinstance(b, list)
    return [a] + b

def car(o):
    assert isinstance(o, list)
    return o[0]

def cdr(o):
    assert isinstance(o, list)
    return o[1:]

def list_ref(o, k):
    assert isinstance(o, list)
    return o[k]

def list_set_x(ls, k, obj):
    assert isinstance(o, list)
    ls[k] = obj
    return None

def even_q(o):
    assert isinstance(o, int)
    return bool(0 == o & 1)

def odd_q(o):
    assert isinstance(o, int)
    return bool(1 == o & 1)

def list_tail(o, k):
    assert isinstance(o, list)
    return o[k:]

def make_list(k, fill):
    return [fill for _ in range(k)]

def zero_q(o):
    assert isinstance(o, int)
    return bool(0 == o)