[Part 2: Fun with type functions](http://channel9.msdn.com/posts/MDCC-TechTalk-Fun-with-type-functions)

I think it is just meant as `\x -> 0 - x`. Lambda abstraction is often written with a dot, see for example the [wikipedia page on lambda calculus](https://en.wikipedia.org/wiki/Lambda_calculus).

Btw, in one of the slides there was a curious lambda abstraction syntax:

    member negate [increment, \x.0-x, negate ]

...but there doesn't seem to be any support for parsing that `\x.0-x` in GHC...

I think it is just meant as `\x -&gt; 0 - x`. Lambda abstraction is often written with a dot, see for example the [wikipedia page on lambda calculus](https://en.wikipedia.org/wiki/Lambda_calculus).

TechTalk: Classes, Jim, but not as we know them (SPJ)