Composable

class discopy.cat.Composable

Bases: ABC, Generic[T]

Abstract class implementing the syntactic sugar >> and << for forward and backward composition with some method then.

Example

>>> class List(list, Composable):
...     def then(self, other):
...         return self + other
>>> assert List([1, 2]) >> List([3]) == List([1, 2, 3])
>>> assert List([3]) << List([1, 2]) == List([1, 2, 3])

abstract then(other, *others)

Sequential composition, to be instantiated.

Parameters:

• other (Composable[T] | None) – The other composable object to compose sequentially.

• others (Composable[T]) –

Return type:

Composable[T]

is_composable(other)

Whether two objects are composable, i.e. the codomain of the first is the domain of the second.

Parameters:

other (Composable) – The other composable object.

Return type:

bool

is_parallel(other)

Whether two composable objects are parallel, i.e. they have the same domain and codomain.

Parameters:

other (Composable) – The other composable object.

Return type:

bool