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feat: generic lens infrastructure

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Edward Langley
2025-06-28 14:47:10 -07:00
parent 7618f95482
commit f9d091759c
1 changed files with 12 additions and 0 deletions
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optics.lisp
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@ -217,3 +217,15 @@ contain the new value at the location focused by the lens."
(set 'a-lens 2
(make-instance 'foo :a 1)))) #|
==> 3 |#)
(defgeneric generic-lens (rec cb loc)
(:method ((rec hash-table) cb loc)
(funcall (funcall (make-hash-table-lens loc)
cb)
rec)))
(defun lens (loc)
"A lens for updating a hash-table, discarding previous values"
(lambda (cb)
(lambda (rec)
(generic-lens rec cb loc))))