[pseudonom-]

That sort of unprincipled, implicit conversion is generally frowned upon (by Elm, Haskell, ML, &c.). It reduces type safety.

If all you want is syntactic sugar, Elm has infix lift operators so:

    let p = lift2 (+) Mouse.x Mouse.y

becomes:

    let p = (+) <~ Mouse.x ~ Mouse.y

If you don't like that, Haskell has `do` notation. If Elm also had it, you could do:

    let p = do
      x <- Mouse.x
      y <- Mouse.y
      return (x + y)