trcks.fp

Example

This example uses the modules trcks.fp.composition and trcks.fp.monads.result to create and further process a value of type trcks.Result:

>>> import math
>>> from typing import Literal
>>> from trcks import Result
>>> from trcks.fp.composition import pipe
>>> from trcks.fp.monads import result as r
>>> GetSquareRootResult = Result[Literal["negative value"], float]
>>> def get_square_root(x: float) -> GetSquareRootResult:
...     return pipe(
...         (
...             x,
...             lambda xx:
...                 ("success", xx)
...                 if xx >= 0
...                 else ("failure", "negative value"),
...             r.map_success(math.sqrt),
...         )
...     )
...
>>> get_square_root(25.0)
('success', 5.0)
>>> get_square_root(-25.0)
('failure', 'negative value')

If your static type checker cannot infer the type of the argument passed to trcks.fp.composition.pipe, you can explicitly assign a type:

>>> import math
>>> from typing import Literal
>>> from trcks import Result
>>> from trcks.fp.composition import Pipeline2, pipe
>>> from trcks.fp.monads import result as r
>>> GetSquareRootResult = Result[Literal["negative value"], float]
>>> def get_square_root(x: float) -> GetSquareRootResult:
...     p: Pipeline2[float, GetSquareRootResult, GetSquareRootResult] = (
...         x,
...         lambda xx:
...             ("success", xx)
...             if xx >= 0
...             else ("failure", "negative value"),
...         r.map_success(math.sqrt),
...     )
...     return pipe(p)
...
>>> get_square_root(25.0)
('success', 5.0)
>>> get_square_root(-25.0)
('failure', 'negative value')