wish: allow a: in the function definition line: function foo(a:line1, a:line2)
Counterwish: implement better semantics for VimScript so that the lookup order of variables alleviates the need for explicit environments. Yes, this will break backwards compatibility.
I personally like both wishes. I don't think that this has to necessarily break backwards compatibility as variables can already have implicit prefixes: eg foo could be l:foo when used in a function or g:foo when used in global scope.
So maybe one could make vimscript search a variable foo as l:foo, a:foo, (maybe also: w:foo, b:foo), s:foo, g:foo, and then throw an undefined variable name error if none exists. Or so.
