Require Import Streams.

Record sAB {A B:Type} : Type := mksAB
{  sA : Stream A
;  sB : Stream B
}.
Arguments mksAB {A B}.

Check const.
Check const 3.
Definition egrec1 := mksAB (const 3) (const true).
Check sA egrec1. 
Check sB egrec1. 

Notation " s '[' name ']' " := (name s) (at level 50).
Check  egrec1 [ sA ].
Check  hd (egrec1 [ sA ]).
Compute  hd (egrec1 [ sA ]).