[aphyr]

Nils are a very bad code smell. They come from C's null, which is a billion dollar mistake[1], according to its creator: Tonny Hoare. Specially now that we have monads[2, 3].

Do you have a source for this? I was under the impression nil was directly taken from Smalltalk, which derived it from Lisp.

[DanielRibeiro]

Wikipedia[1] has the refs:

The null reference was invented by C.A.R. Hoare in 1965 as part of the Algol W language. Hoare later (2009) described his invention as a "billion-dollar mistake":[10][11]

[1] http://en.wikipedia.org/wiki/Null_pointer#Null_pointer

Where:

[10] http://qconlondon.com/london-2009/presentation/Null+Referenc...

[11] http://www.infoq.com/presentations/Null-References-The-Billi...

Yes, the same video I linked above.

[aphyr]

Nil was a part of Lisp 1, which is why I was confused. It predates Algol W by seven years. As null references and nil are somewhat different beasts, I'm not sure the criticism "billion dollar mistake" applies fully.