Next: SRFI-171 Transducers, Previous: SRFI-171 Applying Transducers, Up: SRFI-171 [Contents][Index]

- Scheme Procedure:
**rcons** a simple consing reducer. When called without values, it returns its identity,

`'()`

. With one value, which will be a list, it reverses the list (using`reverse!`

). When called with two values, it conses the second value to the first.(list-transduce (tmap (lambda (x) (+ x 1)) rcons (list 0 1 2 3)) ⇒ (1 2 3 4)

- Scheme Procedure:
**reverse-rcons** same as rcons, but leaves the values in their reversed order.

(list-transduce (tmap (lambda (x) (+ x 1))) reverse-rcons (list 0 1 2 3)) ⇒ (4 3 2 1)

- Scheme Procedure:
**rany***pred?* The reducer version of any. Returns

`(reduced (pred? value))`

if any`(pred? value)`

returns non-#f. The identity is #f.(list-transduce (tmap (lambda (x) (+ x 1))) (rany odd?) (list 1 3 5)) ⇒ #f (list-transduce (tmap (lambda (x) (+ x 1))) (rany odd?) (list 1 3 4 5)) ⇒ #t

- Scheme Procedure:
**revery***pred?* The reducer version of every. Stops the transduction and returns

`(reduced #f)`

if any`(pred? value)`

returns #f. If every`(pred? value)`

returns true, it returns the result of the last invocation of`(pred? value)`

. The identity is #t.(list-transduce (tmap (lambda (x) (+ x 1))) (revery (lambda (v) (if (odd? v) v #f))) (list 2 4 6)) ⇒ 7 (list-transduce (tmap (lambda (x) (+ x 1)) (revery odd?) (list 2 4 5 6)) ⇒ #f

- Scheme Procedure:
**rcount** A simple counting reducer. Counts the values that pass through the transduction.

(list-transduce (tfilter odd?) rcount (list 1 2 3 4)) ⇒ 2.

Next: SRFI-171 Transducers, Previous: SRFI-171 Applying Transducers, Up: SRFI-171 [Contents][Index]