matts-majestic-monads
Release 0.0.5

Monadic data structures

Install: pip install matts-majestic-monads==0.0.5

Documentation

Matts Majestic Monads

This overblown library implements Functor, Applicative and Monad in Python.

Synopsis

You can use Either.convert or Maybe.convert as a decorator to convert return types. This example converts exceptions into Left values:

from monads import Either

@Either.convert
def parse_arguments():
    parser = argparse.ArgumentParser(description='Download a URL and print it')
    parser.add_argument('URL', help='URL to download')
    return parser.parse_args()

Once you have your Either you can use fmap and bind to operate over the contained value:

result = (
    make_parser()
        .fmap(parse)
        .fmap(to_url)
        .bind(read)
)

The methods will be passed the current value. You should use fmap when the function will return a normal value. When the function returns a monad, use bind.

You can use Function as a decorator to convert functions. Once converted they become composable:

from monads import Function

@Function
def parse(parser):
    return parser.parse_args()

@Function
def to_url(arguments):
    return arguments.URL

both = parse.compose(to_url)

Example

There is a simple example of using this library in example.py. This script reads a url that you provide and prints the length of the body:

➜ pipenv run python example.py 'http://python.org/'
Right(48817)

➜ pipenv run python example.py 'http://pythonasdasd.org/'
Left(<urlopen error [Errno -2] Name or service not known>)

Dependencies: 0
Dependent packages: 0
Dependent repositories: 0
Total releases: 5
Latest release: Apr 8, 2019
First release: Apr 5, 2019
Stars: 0
Forks: 0
Contributors: 0
SourceRank: 6

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Releases

0.0.5: Apr 8, 2019
0.0.4: Apr 6, 2019
0.0.3: Apr 5, 2019
0.0.2: Apr 5, 2019
0.0.1: Apr 5, 2019

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Last synced: 2021-02-17 15:36:29 UTC

matts-majestic-monads
Release 0.0.5

Release 0.0.5

0.0.5

0.0.4

0.0.3

0.0.2

0.0.1

Documentation