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malli 2025-05-18
Hi folks, I've got a question about trying to use lazy-cat with malli. Here's a complete example:
(require
'[malli.core :as m]
'[malli.instrument :as mi])
(defn numbers [n]
(lazy-cat (repeat n n) (numbers n)))
(m/=> numbers [:=> [:cat :int] [:sequential :int]])
;(mi/instrument!)
(take 3 (numbers 10))mi/instrument! and re-run the example, I get a stack overflow. It seems like instrumentation causes the infinite seq to be fully realized. Is this a known issue or do I need to write the spec differently?I guess it makes sense since the output would need to be fully realized to ensure everything is valid. The take happens downstream of the spec validation.
opqdonut 2025-05-19T13:05:38.450829Z
yep
Use :every for potentially infinite collections. https://github.com/metosin/malli?tab=readme-ov-file#seqable-schemas
It checks a bounded number of elements (100 by default IIRC).
Nice!!!
It doesn't require sequential? tho fwiw. You might need to use [:and [:every :int] sequential?] if you care about that (relevant for generators).
👍 1
opqdonut 2025-05-20T04:51:05.276749Z
thanks, I didn't know about :every 😅
opqdonut 2025-05-19T05:36:45.423029Z
I don't think malli has anything for lazy validation of lazy sequences. I think you'll just need to skip instrumenting that function.
👍 1