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) – input value

Returns:

boxed value

Return type:

Some(T)

static empty()[source]

Return an empty value

Returns:

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:

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 function to value

Parameters:

f (Callable[[A], B]) – unboxed function

Returns:

boxed return value

Return type:

Option[B]

is_empty()[source]

Return True if the value is empty.

is_some()[source]

Return True if the value is boxed value.

get_or_else(default)[source]

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

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:

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

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

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.