babylon.engine.result

Result type for total functions with explicit error channels.

Spec 040, Discipline 2: Systems return Result[WorldState, TransitionError]. Exceptions are reserved for programmer errors (shape mismatches, missing nodes). Expected failures go through the Result channel.

Usage:

from babylon.engine.result import Ok, Err, Result

def step(state: WorldState) -> Result[WorldState, TransitionError]:
    if wealth < 0:
        return Err(NegativeCapitalStock(node_id="C001", field="wealth", value=wealth))
    return Ok(state.model_copy(update={"tick": state.tick + 1}))

Module Attributes

Result

Type alias for the Result union.

Classes

`Err`(error)	Error variant of Result.
`Ok`(value)	Success variant of Result.

class babylon.engine.result.Ok(value)[source]

Bases: Generic

Success variant of Result.

Holds the successful value from a system step.

Parameters:: value (TypeVar(T)) – The successful result value.

value: TypeVar(T)

is_ok()[source]

Return True — this is a success variant.

Return type:: bool

is_err()[source]

Return False — this is not an error variant.

Return type:: bool

unwrap()[source]

Return the contained value.

Return type:: TypeVar(T)
Returns:: The success value.

map(fn)[source]

Apply fn to the contained value.

Parameters:: fn (Callable[[TypeVar(T)], TypeVar(U)]) – Function to apply to the success value.
Return type:: Ok[TypeVar(U)]
Returns:: New Ok with transformed value.