Prevent fn arrow -> should always be on the same line as fn args

[cschneid]

Function arrows seem somewhat randomly placed.

one with a missing space before

one with a whole line to itself

Spawned from #10

[lpil]

Thank you

[jfornoff]

Not ready to be closed, the spacing around 0-arity function arrows is OK now, but the arrows are still broken into the next lines or parts of the body are put after it.

[lpil]

Thank you :)