My main objection is always readability. Sure, it is nice when I am writing code and on top of my head I know the type of each variable, but when I am reading code, this becomes nightmare for lack of type information.
Strange, that's my objection to type declarations.
Is objectively less readable than
def marketDataService = new Factory<MarketDataService<Stock>>()
And even the latter is not the best.
def MyClass(marketDataService){
this.marketDataService = marketDataService
It's imho the most readable. If the name is self describing and there are unit tests that prove that I'm receiving the correct type I cannot care less about the type itself.
type expression =
| Number of float
| Add of expression * expression
| Subtract of expression * expression
| Multiply of expression * expression
| Divide of expression * expression
let rec eval expr =
match expr with
| Number n -> n
| Add (expr1, expr2) -> (eval expr1) +. (eval expr2)
| Subtract (expr1, expr2) -> (eval expr1) -. (eval expr2)
| Multiply (expr1, expr2) -> (eval expr1) *. (eval expr2)
| Divide (expr1, expr2) -> (eval expr1) /. (eval expr2)