PyMaybe

0.1.6 verified Fri May 01 auth: no python

pymaybe implements Haskell-style Maybe monad in Python, allowing safe chaining of operations on values that may be None. Version 0.1.6 is the latest; releases are infrequent and no breaking changes are documented. The library wraps values in a Maybe container and provides a .maybe attribute for safe access.

pip install pymaybe

Common errors

error AttributeError: module 'pymaybe' has no attribute 'Maybe' ↓

cause Direct import of the module and attempting to use Maybe class directly.

fix

Use from pymaybe import maybe and then maybe(value).

error TypeError: 'Maybe' object is not subscriptable ↓

cause Trying to use bracket indexing on a Maybe object, e.g., maybe_dict['key'].

fix

Use .get('key') method instead of bracket syntax.

Warnings

gotcha Always call .maybe at the end of a chain to unwrap the value; forgetting it returns a Maybe object, causing subtle bugs. ↓

fix Append .maybe to the final expression, e.g., result = maybe(x).get('key').maybe

gotcha The .maybe attribute on a Maybe(None) returns None, but the Maybe object itself is truthy. Use 'value.maybe is None' to check for absence. ↓

fix Use `if result.maybe is None:` instead of `if not result:`

gotcha Arithmetic and comparison operators on Maybe objects behave differently: maybe(5) + maybe(3) returns Maybe(8), but comparing with == checks the wrapped value, not identity. ↓

fix Be aware that operators work on the inner value. For identity checks, unwrap first.

Imports

maybe
wrong
```
import pymaybe
```
correct
```
from pymaybe import maybe
```
Direct import of the module does not expose the 'maybe' factory; must use from-import.

Quickstart

Wrap a dict in maybe() then chain .get() calls; each returns a Maybe object. Access the underlying value via .maybe.

from pymaybe import maybe

# Wrap a potentially None value
data = maybe({'name': 'Alice', 'job': None})
# Safe access using .maybe (returns maybe(None) if missing)
job = data.get('job').maybe
print(job)  # None
# Chaining: get nested key safely
address = data.get('address').maybe.get('city').maybe
print(address)  # None