[plt-scheme] vector-copy in typed scheme

Kind Schemely Folk,

I must be having a brain fart because i'm getting the following
error using vector-copy! from within typed scheme.

typecheck: untyped identifier vector-copy! imported from module 
<typed-scheme> in: vector-copy!

Simply dummy test code at end of message. Stuck in default args in case 
that had some
effect. (Generally wish I had a better mental "machine model" of exactly 
how typed-scheme
worked).

Anyway, odd because build-vector from the same module works just dandy.

Scott

Sill test code follows
----------------------

(define: (a) (vcpy! [dest : (Vectorof a)]
                    [dest-start : Integer]
                    [src : (Vectorof a)]) : (Vectorof a)
      (vector-copy! dest dest-start src 0 1)
      dest)