def expand_clauses(clauses):
if clauses is EmptyList:
return Boolean(False)
first = car(clauses)
rest = cdr(clauses)
if is_cond_else_clause(first):
if rest is EmptyList:
return sequence_expr(cond_actions(first))
else:
raise ValueError('ELSE caluse isn\'t last: %s' % clauses)
else:
return make_if(cond_predicate(first),
sequence_expr(cond_actions(first)), expand_clauses(rest))
def first_operand(ops):
return car(ops)
def operator(expr):
return car(expr)
def first_expr(seq):
return car(seq)
def cond_predicate(clause):
return car(clause)
def first_expr(seq):
return car(seq)
