> Also, typed function parameters are painful. Declaring a parameter as a `f: () -> int` instead of `f` requires that you think about what the signature needs t

> Also, typed function parameters are painful. Declaring a parameter as a `f: () -> int` instead of `f` requires that you think about what the signature needs to be. What if you don't know? Why are you writing the code if you don't know yet what your input will be? A function transforms input into output, how can it do that correctly when you don't know what its input is? If you don't know the input type yet, you should first be writing the things that will deliver the input, or leave the function as an unimplemented placeholder and define only the output type. > What if you want to change it This is one of the best reasons to use types. Directly after the change you'll be told by the compiler which other code needs changes. Compare this to un-typed languages where you'll need a lot of tests to ensure the same or risk runtime errors.