Generators is a library that provides python style generators in common lisp, by using cl-cont delimited continuations
This library is more of an interesting toy, though as far as I know it does work. I dont think I have ever used this in application code, though I think that with care, it could be.
- CL-CONT provides the continuations that make this work
Continuations don't play nicely with exception/signal handling, unwind-protect, throw/catch, or dynamic variables. Consider using cl-cont:without-call/cc, if you need this functionality in a generator. (see-also %mv-gen for an example)
because cl-cont uses a code walker, it might get confused when interacting other code walkers (eg: iterate). Inside of generators, you might have better luck with less code walking
Creates a new generator, the body of which can yield values to the calling scope
yield - returns the next value from the generator to the caller
yielding - yields every value in the passed in generators
(for v in-generator gen)
iterates through the values produced by a generator
(FOR node a-node-of-lisp-tree tree)
iterates through all the nodes of a lisp tree eg: '(1 (2 3) 4) generates (1 (2 3) 2 3 4)
(FOR node a-leaf-of-lisp-tree tree)
iterates through all the leaves of a lisp tree eg: '(1 (2 3) 4) generates (1 2 3 4)
(defun generate-lisp-tree-nodes (trees &optional leaves-only?) "Do a depth first traversal of some set of trees yielding every node/leaf " (make-generator () (iter (for n in (alexandria:ensure-list trees)) (etypecase n (atom (yield n)) (list (unless leaves-only? (yield n)) (yielding (generate-lisp-tree-nodes n)))))))
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