Paste: max-and-position

! The following *almost* works. Problem is that max-and-position doesn't
! have a static stack effect and I get a 'literal expected' error.
!
! Please could someone tell me what I'm doing wrong?
!
! I was hoping to have usage something like
!
! { 2 3 4 5 } [ sqmod ] max-and-position .
!
! => { 9 1 }
!
! Where
!    : sqmod ( n -- n' ) sq 10 mod ;

: 2choose ( x y x' y' ? -- x'' y'' )
    [ [ 2drop ] 2dip ] [ 2drop ] if ;

! (x y) if x>x', else (x' y')
: 2max ( x y x' y' -- x'' y'' )
    [ 3dup nip < ] dip swap
    2choose ;

! Result has effect ( prev elt ind -- next ), where
! prev={oldmax,oldind} and next={fun(elt),ind} or prev.
: [max-position-fun] ( fun -- quot )
    '[
        [ [ first2 ] _ bi* ] dip
        2max 2array
    ] ;

: max-and-position ( seq fun -- max+pos )
    [ dup length iota { -1 -1 } ] dip
    [max-position-fun]
    2reduce ; inline