more convenient function argument typing

[gregwebs]

roy> let f n:Number = n
roy> f 2
2 : Number

roy> let f n:Number n2:Number = n
Error: Parse error on line 2: Unexpected ':'

roy> let f n:Number (n2:Number) = n
Error: Parse error on line 2: Unexpected ':'

roy> let f (n:Number) (n2:Number) = n
roy> f 2 3
2 : Number

All the shifting required is cumbersome. I like the first definition: can the parens be removed for functions with multiple arguments?