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chore: reorganize transducer definition

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Edward
2021-01-04 00:48:49 -08:00
parent 6aebcfe4dc
commit 5bca9a117f
4 changed files with 83 additions and 36 deletions
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58
lazy-sequence.lisp Normal file
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@ -0,0 +1,58 @@
(in-package :data-lens.transducers)
(defclass lazy-sequence ()
((%next :initarg :next :reader next)))
(defun lazy-sequence (next)
(make-instance 'lazy-sequence :next next))
(defmethod reduce-generic ((seq lazy-sequence) (func function) init)
(let ((next (next seq)))
(loop for next-val = (funcall next)
for acc = init then next-acc
for next-acc = (when next-val (funcall func acc next-val))
while next-val
finally (return acc))))
(defmacro repeating (v)
`(lazy-sequence
(lambda ()
,v)))
(defun repeating* (v &key count)
(lazy-sequence
(if count
(let ((iterations 0))
(lambda ()
(when (< iterations count)
(prog1 v
(incf iterations)))))
(lambda ()
v))))
(defun iota (&key (start 0) (step 1) count)
(lazy-sequence
(funcall
(compile nil
`(lambda ()
(declare (optimize (speed 3) (debug 1) (safety 1)))
(let ((init ,start)
,@(serapeum:unsplice (when count
'(iterations 0))))
(declare (type (integer ,start
,(if count
(+ start (* count step))
'*))
init)
,@(serapeum:unsplice
(when count
`(type (integer 0 ,count) iterations))))
(lambda ()
(declare (optimize (speed 3)))
(,@(if count
`(when (< iterations ,count))
'(progn))
(prog1 init
(incf init ,step)
,@(serapeum:unsplice
(when count
'(incf iterations))))))))))))