def parser(token):
if token == '':
return Atom('')
if type(token) == list:
if len(token) == 0:
raise Exception("empty compounds not allowed")
return Compound([parser(x) for x in token])
if type(token) == str:
if len(token) >= 2 and token[0] == '"' and token[-1] == '"':
return String(token[1:-1])
if token == '#f':
return Boolean(False)
if token == '#t':
return Boolean(True)
num = maybe_number(token)
if num is not None:
return Number(num)
if is_identifier(token):
return Identifier(token)
raise Exception(f"invalid token: {token}")
def parser(token):
if token == '':
return Atom('')
if type(token) == list:
## What about empty compounds, are they allowed by the grammar?
return Compound([parser(x) for x in token])
if type(token) == str:
if len(token) >= 2 and token[0] == '"' and token[-1] == '"':
return String(token[1:-1])
if token == '#f':
return Boolean(False)
if token == '#t':
return Boolean(True)
num = maybe_number(token)
if num is not None:
return Number(num)
if is_identifier(token):
return Identifier(token)
## Actually nice error messages
raise Exception(f"invalid token: {token}")