Can compiler macros make use of type declarations?

[Steve Losh]

Check out Bike's compiler-macro library, specifically the `form-type`
function: https://github.com/Bike/compiler-macro

On Mon, Nov 6, 2017 at 3:43 PM, Chaitanya Gupta <mail at chaitanyagupta.com> wrote:
> Let's say I have created a function called `FOO`:
>
> (defun foo (x)
>   ...)
>
> To optimize this function, I write a compiler macro. Can I make use of
> type declarations that users of `FOO` might have made for the argument
> `X` that is passed in to it?
>
> That is, let's say `FOO` is used like this:
>
> (let ((a (something-that-returns-an-integer)))
>   (declare (integer a))
>   (foo a))
>
> The compiler macro for `FOO` cannot make any optimizations on the
> value of `A`, but can it take advantage of the fact that `A` is
> declared as in `INTEGER` here?
>
> Chaitanya
>