Expansion brackets.

[MattyCrowther]

Expansion and Parameter list contains the same brackets ().
Might be useful to change expansion brackets to either:
{}
[]
<>
WhiteSpace.

[lgrozinger]

I like the whitespace idea, because I think that non-programming users are in general a little put-off by an over-abundance of brackets.

We'd have to figure out in the parser how to separate the argument list from the body of the expansion though, since shift/reduce conflicts would inevitably result from an 'any whitespace' rule. This probably isn't trivial, but it could be done by adding some backtracking logic to the parser.