Not composable: maybe([None])[0].is_none()

[nyanpasu64]

• Kubuntu 18.04 x64
• Anaconda 3.6, pip install pymaybe
• maybe([None])[0].is_none() is True.
• maybe([None])[0].get() raises Exception, despite [None][0] is None.
• maybe({'a': None})['a'].get() raises Exception, despite {'a': None}['a'] is None.

https://www.lucidchart.com/techblog/2015/08/31/the-worst-mistake-of-computer-science/

Despite being a maybe "implementation", this library fails to distinguish a missing element from a deliberate None value.

[akazukin5151]

Just change this to return Nothing()

pymaybe/pymaybe/__init__.py

Lines 23 to 24 in f755600

	def get(self):
	raise NothingValueError('No such element')

Seems like you're supposed to use the or_else() method instead of get(), but then why provide a get() method anyway?

[georgipopovhs]

There is a similar issue also with obj.member = None; maybe(obj).member.get().
I think the root cause is maybe(None).get() raises.
To me it's more logical to have maybe(None).get() == None.
This can be done if we update the code to have maybe(None) == Something(None).