 M: output-cursor set-cursor-value-unsafe set-cursor-value ; inline
 M: output-cursor set-cursor-value
     dup cursor-valid? [ set-cursor-value-unsafe ] [ invalid-cursor ] if ; inline
+
+!
+! stream cursors
+!
+
+MIXIN: stream-cursor
+INSTANCE: stream-cursor forward-cursor
+
+M: stream-cursor cursor-compatible? 2drop f ; inline
+M: stream-cursor cursor-valid? drop t ; inline
+M: stream-cursor cursor= 2drop f ; inline
+
+MIXIN: infinite-stream-cursor
+INSTANCE: infinite-stream-cursor stream-cursor
+
+M: infinite-stream-cursor inc-cursor ; inline
+
+MIXIN: finite-stream-cursor
+INSTANCE: finite-stream-cursor stream-cursor
+
+SINGLETON: end-of-stream
+
+GENERIC: cursor-stream-ended? ( cursor -- ? )
+
+M: finite-stream-cursor inc-cursor
+    dup cursor-stream-ended? [ drop end-of-stream ] when ; inline
+
+INSTANCE: end-of-stream finite-stream-cursor
+
+M: end-of-stream cursor-compatible? drop finite-stream-cursor? ; inline
+M: end-of-stream cursor-valid? drop f ; inline
+M: end-of-stream cursor= eq? ; inline
+M: end-of-stream inc-cursor ; inline
+M: end-of-stream cursor-stream-ended? drop t ; inline
 
 !
 ! basic iterator

    { growable read-only } ;
C: <pusher-cursor> pusher-cursor

INSTANCE: pusher-cursor forward-cursor

! XXX define a protocol for stream cursors that don't actually move
M: pusher-cursor cursor-compatible? 2drop f ; inline
M: pusher-cursor cursor-valid? drop t ; inline
M: pusher-cursor cursor= 2drop f ; inline
M: pusher-cursor inc-cursor ; inline

INSTANCE: pusher-cursor output-cursor

M: pusher-cursor set-cursor-value growable>> push ; inline

GENERIC: begin-cursor ( collection -- cursor )
GENERIC: end-cursor ( collection -- cursor )

: all ( collection -- begin end )
    [ begin-cursor ] [ end-cursor ] bi ; inline

: all- ( collection quot -- begin end quot )
    [ all ] dip ; inline

!
! containers
