List parser

This output parser can be used when you want to return a list of comma-separated items.

from langchain.output_parsers import CommaSeparatedListOutputParser
from langchain.prompts import PromptTemplate
from langchain.llms import OpenAI

output_parser = CommaSeparatedListOutputParser()

format_instructions = output_parser.get_format_instructions()
prompt = PromptTemplate(
    template="List five {subject}.\n{format_instructions}",
    input_variables=["subject"],
    partial_variables={"format_instructions": format_instructions}
)

model = OpenAI(temperature=0)

_input = prompt.format(subject="ice cream flavors")
output = model(_input)

output_parser.parse(output)

The resulting output will be:

    ['Vanilla',
     'Chocolate',
     'Strawberry',
     'Mint Chocolate Chip',
     'Cookies and Cream']