add filters to prompt function

[derfred]

Allow giving custom filters to the prompt decorator

def reverses: str) -> str:
    return s[::-1]

@prompt(filters=[reverse])
def reverse_prompt(text):
    '''{{ text | reverse }}'''

prompt = reverse_prompt("Hello")

print(prompt)
>>> "olleH"

[rlouf]

filters should be a simple argument that has type Dict[str, Callable] and maps the filter names to the functions.

[rlouf]

I generally don't mind a little repetition but I think we should refactor the code and add a create_environment class that can be used in both class methods. @yvan-sraka are there any reasons we shouldn't do that?

[derfred]

thanks for your review @rlouf. I've taken your comments into account. While doing so the following alternative approach came to me:

env = outlines.prompts.prompt_environment([reverse])

@env
def my_prompt(text):
  "reversed: {{ text | reverse }}"

what do you think?