Pynction 🐍
Functional based library to support haskell monads like Either, Maybe in a scala fashion style. The library also contains Try monad inspired from vavr and a Stream class which is pretty similar to scala and java stream API
Inspired in: VΛVR
Why should you use it ?
Probably if you have reached this library you already know something about functional programming and Monads.
Well this library is another one that empowers your imperative code to start using functional programming concepts. This type of programming makes your code declarative as long as give you support to the most famous monads like Maybe
and Either
.
These monads make your interfaces explicit for error handling so paraphrasing If it compiles, it works
this time it is If mypy is happy, your code works
Basic examples
Stream examples
from pynction import stream_of, stream
foo = (
stream_of([1, 2, 3, 4])
.map(lambda a: a + 1)
.filter(lambda n: n % 2 == 0)
.flat_map(lambda n: [n, n * 2])
.to_list()
)
bar = (
stream("example", "e", "something")
.take_while(lambda s: s.startswith("e"))
.to_list()
)
Maybe examples
from pynction import maybe, nothing
def divide_10_by(n: int) -> Maybe[int]:
if n == 0:
return nothing
return maybe(10 / n)
result = divide_10_by(2).get_or_else_get(-1)
result = divide_10_by(0).get_or_else_get(-1)
Try examples
from pynction import try_of
def add_10(n: int) -> int:
if n > 10:
raise Exception("n must be less than 10")
return n + 10
try_example_1 = try_of(lambda: add_10(11)).map(lambda a: a + 1)
try_example_1.on(
on_success=lambda a: print(f"Result: {a}"),
on_failure=lambda e: print(f"Error: {e}"),
)
try_example_2 = try_of(lambda: add_10(9)).map(lambda a: a + 1)
try_example_2.on(
on_success=lambda a: print(f"Result: {a}"),
on_failure=lambda e: print(f"Error: {e}"),
)
Either examples
from pynction import left, right, Either
LESS_THAN_10_LETTERS = Literal["LESS_THAN_10_LETTERS"]
GREATER_THAN_100 = Literal["GREATER_THAN_100"]
WordTransformationError = Literal[LESS_THAN_10_LETTERS, GREATER_THAN_100]
def make_upper_case_first_n_letters(word: str, number: int) -> Either[WordTransformationError, str]:
if len(word) < 10:
return left("LESS_THAN_10_LETTERS")
elif number > 100:
return left("GREATER_THAN_100")
else:
return right(word.upper()[0:number])
result = make_upper_case_first_n_letters("example", 10)
print(result)
API
Check the docs