Option¶

class towhee.functional.Option[source]¶

Bases: Generic[A]

Functional-style error handling.

Option[A] = Some(A) or Empty[A] 1. Some(A): just a container for result; 2. Empty[A]: result is empty, because of input error or computation error;

Examples

>>> a = Some(10)
>>> a.map(lambda x: x/2.0)
Some(5.0)

>>> a.map(lambda x: x/0)
Empty()

>>> b = Empty()
>>> b.map(lambda x: x/2.0)
Empty()

static of(x: T)[source]¶

Return a boxed value.

Parameters:: x (T) – The input value.
Returns:: The boxed value.
Return type:: Some(T)

static empty()[source]¶

Return an empty value.

Returns:: The empty value.
Return type:: Empty

flat_map(f: Callable[[A], Option[B]]) → Option[B][source]¶

Apply boxed version of callable.

Parameters:: f (Callable[[A], Option[B]]) – Boxed version of callable
Returns:: The boxed value.
Return type:: Option[B]

Examples

>>> Option.of(1).flat_map(lambda x: x+1)
2

>>> Option.empty().flat_map(lambda x: x+1)
Empty()

map(f: Callable[[A], B]) → Option[B][source]¶

Apply a function to a value.

Parameters:: f (Callable[[A], B]) – A unboxed callable.
Returns:: The boxed return value.
Return type:: Option[B]

is_empty()[source]¶

Return True if the value is empty.

Returns:: True if empty.
Return type:: bool

is_some()[source]¶

Return True if the value is boxed value.

Returns:: True if boxed.
Return type:: bool

get_or_else(default)[source]¶

Return unboxed value, or default if the value is empty.

Parameters:: default (any) – The default value to return.
Returns:: The unboxed value, or default if empty.
Return type:: any

Examples

>>> Option.of(0).get_or_else(1)
0

>>> Option.empty().get_or_else(1)
1

__weakref__¶: list of weak references to the object (if defined)

class towhee.functional.Some(x: A)[source]¶

Bases: Option[A]

Some value for Option

__init__(x: A) → None[source]¶

__repr__() → str[source]¶: Return repr(self).

flat_map(f: Callable[[A], Option[B]]) → Option[B][source]¶

Apply boxed version of callable.

Parameters:: f (Callable[[A], Option[B]]) – Boxed version of callable
Returns:: The boxed value.
Return type:: Option[B]

Examples

>>> Option.of(1).flat_map(lambda x: x+1)
2

>>> Option.empty().flat_map(lambda x: x+1)
Empty()

get()[source]¶: Return unboxed value

class towhee.functional.Empty(x: Optional[Any] = None, e: Optional[Exception] = None)[source]¶

Bases: Option[A]

Empty value for Option

Parameters:

x (Any, optional) – The value. Defaults to None.
e (Exception, optional) – The reasone for value. Defaults to None.

__init__(x: Optional[Any] = None, e: Optional[Exception] = None) → None[source]¶

__repr__() → str[source]¶

The repr function that returns default ‘Empty()’.

Returns:: Returns ‘Empty()’.
Return type:: str

flat_map(f: Callable[[A], Option[B]]) → Option[B][source]¶

Apply boxed version of callable.

Parameters:: f (Callable[[A], Option[B]]) – Boxed version of callable
Returns:: The boxed value.
Return type:: Option[B]

Examples

>>> Option.of(1).flat_map(lambda x: x+1)
2

>>> Option.empty().flat_map(lambda x: x+1)
Empty()

get()[source]¶

Return the reason of the empty value.

Returns:: Reason for empty.
Return type:: _Reason