https://github.com/lewisgaul/python_adt

Implementation of Alegbraic Data Types (ADTs) in Python
https://github.com/lewisgaul/python_adt

algebraic-data-types python3 sum-types tagged-unions

Last synced: 4 months ago
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Implementation of Alegbraic Data Types (ADTs) in Python

• Host: GitHub
• URL: https://github.com/lewisgaul/python_adt
• Owner: LewisGaul
• License: mit
• Created: 2021-02-20T22:33:04.000Z (over 5 years ago)
• Default Branch: main
• Last Pushed: 2025-02-17T23:19:21.000Z (over 1 year ago)
• Last Synced: 2025-12-21T19:38:45.541Z (7 months ago)
• Topics: algebraic-data-types, python3, sum-types, tagged-unions
• Language: Python
• Homepage: https://adt.readthedocs.io
• Size: 39.1 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 5
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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# Algebraic Data Types in Python

```python

import adt

class MyADT(adt.ADT):

    foo: ()

    bar: (int,)

    baz: (int, bool, str, None)

    @adt.fieldmethod

    def double_first(field, basecls) -> "MyADT":

        if isinstance(field, basecls.foo):

            raise TypeError(

                f"{basecls.foo.__qualname__} does not support doubling"

            )

        field_type = type(field)

        first, *rem = field

        return field_type(first * 2, *rem)

foo = MyADT.foo()

bar = MyADT.bar(4)

baz = MyADT.baz(3, False, "hi", None)

for val in [foo, bar, baz]:

    print(val)

    try:

        doubled = val.double_first()

        print("Doubled:", doubled)

    except TypeError:

        print("Failed to double")

    print()

```

See `examples/`, `adt/example.py` and `tests/test.py`.