oslash

library2.0.0pypypi✓ verified 92d ago

A functional programming library providing Functors, Applicatives, and Monads for Python 3.12+. Current version 2.0.0, stable release with PEP 695 type parameters and strict type checking. Maintained on an irregular cadence by dbrattli.

serialization

pip install oslash

github ↗package ↗

INSTALL

IMPORT

SIG · OSLASH

oslash

serializationpythonv2.0.0

Install

1.6s avg

Import

59ms

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.6.3 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.064s · 18.4MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.054s · 19MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Maybe

✓ from oslash import Maybe

Direct import from oslash package, no submodule needed.

Either

✓ from oslash import Either

Import Either directly from oslash.

List

✓ from oslash import List

Import List (a monadic list wrapper) directly from oslash.

Basic usage of Maybe monad with map and bind (>>).

from oslash import Maybe, Just, Nothing result = Just(42).map(lambda x: x * 2) print(result) # Output: Just(84) result2 = Nothing() >> (lambda x: Just(x * 2)) print(result2) # Output: Nothing()

Debug

Known issues

breakingPython 3.12 minimum: OSlash v2.0.0 requires Python 3.12+ and will not install on older versions.

fix

Upgrade to Python 3.12 or higher, or pin to an older OSlash version (<2.0.0) if you must use an older Python.

affects: >=2.0.0

deprecatedOld import paths like `from oslash.maybe import Maybe` or `from oslash.either import Either` no longer work in v2.0.0.

fix

Use direct imports: `from oslash import Maybe, Either, List`.

affects: >=2.0.0

gotchaThe `List` monad's `bind` (>>) expects a function that returns a list of monadic values, not a plain list. Misuse can lead to unexpected behavior.

fix

Always wrap plain values in the monad (e.g., `lambda x: Just(x)`) when using >>.

affects: *

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'oslash.maybe'

In OSlash v2.0.0, submodules like `oslash.maybe` were removed in favor of direct imports.

fix

Change import from `from oslash.maybe import Maybe` to `from oslash import Maybe`.

TypeError: unsupported operand type(s) for >>: 'NoneType' and 'function'

Used `>>` on Python's built-in None instead of OSlash's Nothing() singleton.

fix

Use `Nothing()` from oslash instead of plain `None`.

ImportError: cannot import name 'Right' from 'oslash'

`Right` and `Left` constructors are not exported; use `Either.right` and `Either.left` methods or the class constructors.

fix

Use `from oslash import Either; value = Either.right(42)` or `Either(42, is_right=True)`.

AttributeError: 'Maybe' object has no attribute 'bind'

The method for monadic bind is `>>` operator, not `.bind()`.

fix

Use `>>` operator, e.g., `maybe >> lambda x: Just(x+1)`.

Upgrade

Version history

2.0.0latest on PyPI · released Nov 17, 2025

Audit

Dependencies

No dependency data recorded yet.

Agent activity

11 hits · last 30 days

node

Anthropic

Resources

githubhttps://github.com/dbrattli/oslash ↗

packagehttps://pypi.org/project/oslash/ ↗