Produces each period of the item stream stream in its strict retrograde form, no matter what pattern stream implements.

Example:

? (setf x (retrograde (steps 1 2 in random for 8 from 'c4))
#<FUNCTIONAL-ITEM-STREAM 131442261>

? (read-items x)
(GS4 G4 FS4 F4 DS4 D4 CS4 C4)

? (read-items x)
(C5 AS4 GS4 FS4 E4 D4 CS4 C4)

? (read-items x)
(AS4 A4 G4 F4 E4 DS4 CS4 C4)

See Also: