def _parse_boolean(token_supply):
"""Parse a boolean literal."""
boolean_token = token_supply.next()
assert isinstance(boolean_token, tokens.BooleanLiteral)
text = boolean_token.text.lower()
if text == '#t':
return datatypes.lisp_bool(True)
elif text == '#f':
return datatypes.lisp_bool(False)
else:
raise ValueError('Unexpected boolean literal `%s`.' % text)
def _parse_boolean(token_supply):
"""Parse a boolean literal."""
boolean_token = token_supply.next()
assert isinstance(boolean_token, tokens.BooleanLiteral)
text = boolean_token.text.lower()
if text == '#t':
return datatypes.lisp_bool(True)
elif text == '#f':
return datatypes.lisp_bool(False)
else:
raise ValueError('Unexpected boolean literal `%s`.' % text)
def _le(left, right):
return datatypes.lisp_bool(left <= right)
def _is_vector(candidate):
return datatypes.lisp_bool(isinstance(candidate, datatypes.Vector))
def _ge(left, right):
return datatypes.lisp_bool(left >= right)
def _lt(left, right):
return datatypes.lisp_bool(left < right)
def _gt(left, right):
return datatypes.lisp_bool(left > right)
def _is_truthy(value):
"""Return False iff value is #f."""
# Scheme defines nearly everything to be truthy. Only #f is falsey!
# TODO(jasonpr): Consider violating the Scheme spec, and doing
# something more Pythonic.
return value != datatypes.lisp_bool(False)
def _is_truthy(value):
"""Return False iff value is #f."""
# Scheme defines nearly everything to be truthy. Only #f is falsey!
# TODO(jasonpr): Consider violating the Scheme spec, and doing
# something more Pythonic.
return value != datatypes.lisp_bool(False)